Monday, December 12, 2016

Atlanta Parcel Data

Fulton County provides detailed property assessment data online, including property assessment, home age, and the property shapefile. The map below uses this data to show the construction date of each building in Inman Park:

Inman Park has several homes built before 1900, but the two most common decades are the 1920's and the 2000's. Scroll down for an interactive version with hover-over (best on a computer).

The next visual shows median home age by neighborhood. The oldest Atlanta neighborhoods are near downtown. These neighborhoods include Inman Park, Midtown, Adair Park, and Grant Park, all of which have a median home age of 1920. The visual also allows the user to add condos and town-homes to the median age, which changes the age significantly for some neighborhoods.

Unfortunately, the ages of homes built in the 1960's or earlier are only approximate. The graph below shows that home ages in the county data tend to be rounded to the nearest five or ten years.

This graph also suggests that the listed age of many homes that are older than 1920 are rounded up to 1920. If you people would like to help me out, you could spend several days researching the age of your home and your neighbors' and contacting the Fulton assessment office to correct the age. I understand that this can be approximated by looking at historical plat records, but several minutes of googling didn't tell me how to find those. (Update: see links at bottom of post.)

To view a map of home ages for any Atlanta neighborhood in Fulton County, use the interactive below. Mouse over a parcel to see more details or use the zoom tools in the upper left.

Dekalb County does not have similar data files publicly available. City of Atlanta has a parcel shapefile that includes Dekalb county, but the data is a few years old and has limited fields. Both counties have very functional interactive GIS maps online (FultonDekalb), and property lookups (FultonDekalb).

The parcel data can also be used to map appraisal values. Here's Morningside/Lenox by appraisal value:

The modal appraisal value is $500-600K, but there are a few homes appraised at over $2 million. Cross-checking with Zillow shows that homes in Morningside/Lenox tend to be listed for about 20% more than their appraisal value. 

Morningside/Lenox is actually a little larger to the east than the above map portrays, but that portion is in Dekalb County.

Use the interactive tool below to view appraisal data for any Atlanta neighborhood in Fulton County. 

We can also view average appraisal value by neighborhood on the map below. I've made a similar map using Zillow data, but the map using appraisals covers more neighborhoods and includes values of all homes. On the other hand, appraisal values are often lower than actual sale prices.

The map above also allows the user to add condos and town-homes. This feature demonstrates the importance of density for affordability. When condos and town homes are excluded, Midtown contains 752 homes with a median value of $498K. When condos and town homes are included, Midtown contains 8,920 homes with a median value of $207K.

Let me know in the comments or on twitter if you have questions or find anything interesting in the data.

Update: a helpful commenter from reddit shared a few links to research home ages:

BTW, there's a great resource for researching your property's history hereYou aren't going to find historical plat records, the best you can do is the old Sanborn Fire Insurance mapsThose will at least show you the shape of the building. There are some other great historic city maps here.

Wednesday, October 19, 2016

Atlanta MARTA Expansion

Atlanta voters will decide on a 0.5% sales tax to fund MARTA expansion this election. Major components of the plan include light rail on the BeltLine, more streetcar lines, and new MARTA stops on BeltLine intersections. 

MARTA has posted slides of planned expansion projects, but I have not seen projected ridership or a cost-benefit analysis. I consider the project in multiple ways below and decide that voters should not approve the tax. The proposed additions are poor choices, Atlanta residents have not demonstrated sufficient demand, the expansion would not be cost-effective, and MARTA already has growing funding sources.

Project Selection


This is the most obvious argument in a long list. In addition to a proposed streetcar extension, there are also street-level light rails that appear to be a streetcar by another name. Any proposal that includes streetcars is not a serious proposal for public money. It's ludicrous to me that our city would spend $100 million to install three miles of train tracks in a functioning street to do exactly what a bus can already do, with the exception of not being able to avoid obstacles or re-route during street closures.


The current project plan is not MARTA's first choice. The agency had plans for an $8 billion expansion last year that included a northern expansion of heavy rail. However, funding for that plan was not approved. Instead, MARTA received permission for a referendum on sales tax in the city of Atlanta only, so they've developed a second plan, mostly inside city limits. This is significant because only 10% of the metro area's population lives inside the city. A public transit solution focused inside city limits is unlikely to have a large impact on congestion.

In addition to a limited geographic focus, the new plan does not serve the city's highest density areas. Consider the map below, which overlays MARTA stops and the BeltLine on top of a density map of Atlanta. The density map includes both residents and jobs. Existing MARTA rail has good coverage through the densest areas of downtown and midtown Atlanta. The BeltLine, on the other hand, circles the city mostly through less-dense areas. 

The busiest MARTA stops are those in high-density areas downtown, and those at the terminals, used as connectors for commuters who live outside the bounds of MARTA. Some of the least-busy stops are the intermediate east-west stops near the BeltLine. Residents there live in neighborhoods that are not dense enough to have large populations close to the station, and live close enough to downtown that waiting for a train isn't as fast as driving. BeltLine transit would be even less useful for these residents. Most riders would then have an additional transfer to get to their destination off the BeltLine, which further increases travel time and decreases use.

Project List

The project list includes $11.9 billion in costs. The cost estimates suggest $3.2 billion could be covered by federal grants, leaving $8.7 billion for the city. Of course, cost projections and ability to win federal grants are usually optimistic, so the price tag could be significantly higher. The proposed tax is projected to raise $2.5 to $3.5 billion over 40 years. Because the project cost exceeds the revenue, voters do not actually know what they are voting for- some parts might not be built at all, and some will be built regardless of the referendum, through BeltLine funding or growth in MARTA’s current revenue sources.

Demand for Public Transit


Trends over time are also helpful for thinking about the need for MARTA expansion. The graph below shows the percent change in the population, public transit usage, and traffic delay for the Atlanta metro area. The metro population grew 23% from 2002 to 2014, but public transit usage fell by 9.1% and traffic congestion fell by 3.7%. 

MARTA advocates have said that more public transit is needed for a growing population, but the trends over time do not support that claim. Although the population is growing, congestion and public transit use have not increased. Perhaps people are living closer to work, are more likely to telecommute, or traffic management has improved. Traffic patterns could change even more moving forward with the roll-out of self-driving cars. Atlanta should not commit to a new 40-year multi-billion dollar tax for transit infrastructure when demand is not growing and the future is even less certain.

The rising population leads to another interesting point. The majority of MARTA's current funding is through a sales tax. As the population grows, MARTA's funding increases, even though their ridership has not. Sales tax revenue from the growing population should then allow MARTA to pay for gradual expansions without new taxes.


People who complain about Atlanta public transit often compare Atlanta to other cities with more public transit, like DC. But these comparisons are tenuous. DC is far denser than Atlanta, and public transit is much more effective in dense cities. Observe the relationship between density and transit use in large US cities. (From an earlier post
Daily trips assumes two unlinked trips per day):

Atlanta is one of the least dense cities in the US, but for our level of density we have more transit usage than other similar cities. 

Given that we already have high public transit use relative to density, building more transit is less likely to be a high-return investment.

Another interesting cross-city comparison is total commute time. Atlanta has the tenth longest commute times on this list, but about expected for a major city. Denser cities like New York, DC, and Boston have more public transit usage and longer commute times than Atlanta. These cities, of course, have a different commuting problem than Atlanta. Travel speed is slower in high-density cities because there are even more people in the way, and public transit makes sense for more commuters. However, Atlanta travel times are high because people are more spread out and have farther to go. Imposing the solution that works in New York or DC doesn't make sense for Atlanta.

Cost Benefit

One of the main benefits of public transit is that it removes cars from the road, which reduces traffic for other drivers. The Texas A&M Transportation Institute calculates the cost of congestion per driver for cities in the US. The Atlanta cost in 2014 is $1,130 per driver. This works out to $2.17 per commuting trip (2 trips per day, 261 work days per year). 

The external cost of commuting is similar to the operating cost of MARTA: the cost per trip for rail was $2.05 and the cost for bus (1) was $2.74. (Costs are net of fare- rail cost per trip was $3.14, minus an average fare of $1.09.) This seems to work out nicely- taxpayers are subsidizing public transit by the same amount we benefit by reducing traffic. However, this only includes the operating costs of MARTA, and not the capital costs. Capital costs are almost half of MARTA's total budget, so the total public subsidy to each ride is actually $4-$5, which is much greater than congestion costs.

Not only are current MARTA options not cost effective, but the proposed options will be even less so. The proposed options are in sub-optimal locations, which will reduce cost effectiveness, and the proportion of capital costs will be even higher, as the lines are not yet constructed. 


One of the arguments for public transit that is not necessarily addressed by cost benefit concerns is equity. Public transit through poor neighborhoods will give the poor access to more jobs, retail, and services and promote revitalization. Although the access component might be true (if usage is reasonably high), the revitalization component has not happened at current MARTA stops.

MARTA did not receive a single market-rate housing proposal for the Oakland City transit-oriented development project. Also, several neighborhoods near south and west MARTA stops have very low home values- several below $50 per square feet. Neighborhoods with existing rail are not being revitalized, so we shouldn't assume new rail would have a different effect. Public money would be better spent improving schools and crime in Atlanta's poorest neighborhoods, or creating more targeted attempts at investment. Also, voting against the tax does not eliminate public transit from BeltLine neighborhoods; they will still be served by bus.


The idea of public transit is inspirational- it's a public good that helps the poor, it connects communities, and reduces traffic congestion and pollution. Voting to support public transit gives a voter a warm glow. But let's consider not just the proposed funding, but current funding as well.

MARTA funding began with a 1971 vote that approved a 1% sales tax in Fulton and Dekalb counties. The sales tax was originally scheduled to drop to 0.5% but the 1% rate has been repeatedly extended, most recently in 2007 for a list of projects that included BeltLine transit. As explained above, the 1% sales tax is already a growing revenue stream as the population increases.

In addition to the current 1% MARTA sales tax, BeltLine transit also receives funding from the BeltLine tax allocation district (TAD). Property taxes from new developments and rising home values in the BeltLine TAD pay back the bonds used for BeltLine construction. So the proposed sales tax increase would be the third revenue source passed using the BeltLine as justification for funding.

Further, between the proposed MARTA tax and City of Atlanta infrastructure tax, Atlanta sales tax rates would rise to 8.9%- nearly the state maximum of 9.0%. This would limit the city's flexibility to raise future funds for valuable projects- especially since the new 0.5% MARTA tax would be locked in for 40 years.


We’re fortunate to live in a growing city- Atlanta will develop in exciting ways in the next forty years. But our optimism shouldn’t cause us to approve any public transit plan. Our leaders need to be accountable- present a plan of exactly what will be built, instead of presenting three times as many projects as the tax can fund. Build in neighborhoods that demonstrate demand for transit. Make a case for cost-effectiveness. And don’t build more ridiculous streetcars.

Wednesday, July 6, 2016

Atlanta Commuting Patterns

MARTA's proposed expansion plan has made me think about where people live and work in the city. A friend recently introduced me to the LEHD Origin-Destination Employment Statistics data which has work and home data by census block. This data shows interesting commuting trends in Atlanta. For example, most people who work at or near the airport tend to live south of the perimeter:

Most common home locations of employees at/near the airport

Larger end points indicate more people. Census tracts that make up less than 0.25% of the workforce are not included. So there are other employees north of the airport, just not enough to include in the map. The interactive version below has a tab, "Dots", that includes all locations and mouse-over that shows the actual number and percentage of commuters.

Another interesting census tract is the one that contains Emory University:

Most common home locations of employees at/near Emory

Emory employees tend to live close to campus or farther east. Notice the Emory image is more zoomed-in than the airport, and still shows most employees.

Neighboring census tracts can have much different commuting patterns. The south downtown census tract that includes city hall has employees who mostly commute from further south:

Most common home locations of south downtown employees (includes city hall)

And the downtown census tract that includes the Coke headquarters has more employees that commute from north of the office:

Most common home locations of north downtown employees (includes Coke)
I use Coke as an example of a well known employer in that census tract. But both of the downtown census tracts described span several blocks, and contain multiple employers. The interactive tool below shows this more clearly. Use the zoom tools in the upper left to more closely see which neighborhoods are covered. Or try the "Dots" tab to see a more complete view.

The visual also allows you to toggle from viewing all home locations of a given work location to viewing the reverse- all work locations of a given residential neighborhood. Using this option, I can see that most people in my neighborhood commute to downtown/midtown, or north to Emory or further. Very few commute south or east.

Most common work locations of residents in my census tract (West Kirkwood)
I started this data analysis as part of a post on the MARTA expansion, but decided on a stand-alone post. If you're interested in the MARTA post, follow me on twitter of google+, or use the e-mail subscription box on the right.

Sunday, June 12, 2016

Senators who voted against the Assault Weapons Ban

I'm feeling angry and upset about the mass killing in Orlando. My earlier, more hyperbolic title was, "Does your Senator support Terrorism?" but I've edited it to something more precise.

You can call, e-mail, or write your senators with this link, or find your congressperson here.

An assault weapons ban wouldn't affect most murders in the US, but it would be a good start. Here's a nice article by Adam Gopnik that suggests other sensible gun control steps.

Information on the 2013 assault weapons bill is here or here.

Sunday, May 15, 2016

WNBA Data Visuals: 2015 Season

I made a series of data visuals to understand the WNBA. Preview below; the full blog is posted at my new dynamic site (for mobile-responsive data views).

Tuesday, May 10, 2016

City of Atlanta Budget, FY2017

The City of Atlanta recently released their proposed Fiscal Year 2017 budget. The city provides a 640-page document explaining the budget, as well as interactive data visuals in the Atlanta Budget Explorer (ABE). I was part of the team that created ABE in 2014 after we built a prototype in a city hackathon. To supplement the information in ABE this year I created the interactive visuals below to explore the 2017 proposed budget.

The first visual shows the 2017 budget by department, and the changes from the 2016 budget in both dollar amounts and as a percentage. The visual is interactive; click a department to view spending by office and account.

The data show the police department is the largest city department at $181.39 million, which is a $6.8 million increase from 2016, or 3.9%. However, if you click on the police services, you'll see that the budget for uniform patrol has dropped by 1.5% (closer to 3% in real terms, assuming inflation). The Account drill-down shows that total salaries for sworn officers is increasing by 2.1%, so the decline in uniform patrol spending does not indicate a decline in the total number of officers. The budget book (p. 75) confirms there is not a decline in staff. 

The largest increase in the police department is $6.29 million for "SSP Administration". Consulting the budget book (p. 351), I can see that "SSP" is the "Strategy and Special Projects Division". However, it is unclear to me whether the SSP increase is new spending, or just a re-organization of existing services (perhaps out of uniform patrol, explaining the decrease). This is a good example of the breadth and limitations of the budget data used to create the visuals. As one might expect, the budget data set does not have detailed department descriptions or narratives. Therefore, the budget book is a useful compliment. For more detail, you can attend the public hearing on May 12 or email the city council.

The next visual shows budget changes by department over time. This visual is also interactive by clicking a department.

This view shows which departments have been consistently growing, such as city council, whose budget rose from $6.37 million in 2013 to a proposed $12.71 million in 2017.

The last visual shows revenue, both the 2017 amounts and the multi-year changes.

Property tax is the largest source of city revenue, but the visual shows the city raises money in several different ways. Property tax revenue is projected to fall this year, despite the city's growth. This is because some of the city's new construction falls in Tax Allocation Districts and due to roll-backs from the Georgia Taxpayer Bill of Rights.

The visuals above only show budget and revenue from the city's general fund. Both ABE and the budget book have more details on other funds, such as special revenue.

Of course the budget data and budget book don't answer every question about the budget (and can't be expected to do so), but both the level of detail and the accessibility of the information are impressive.

Update: Councilman Alex Wan has a nice Youtube video encouraging engagement in the budget process.

Wednesday, April 13, 2016

Six Months of Home-Cooked Meals

I'm lucky that my wife is great at cooking and meal-planning. To do my part, I made a spreadsheet that tracks our meals and related data points (taste rating, cost, etc...). So, um, my wife is lucky too?

The visual below shows the first six months of data.

The top half shows all the meals we recorded for the past six months. Use the protein menu in the top right to filter the data, or click on an icon to get a link to the recipe. 

The bottom half sorts the the recipes according to the parameters on the lower left. The default position uses taste as the most important parameter (10), and price as the least important (3). Adjust the sliders to resort. The bottom half also has a filter for protein choice, and for whether the recipe is online. (Many of our recipes come from two different cookbooks by Mark Bittman, and some were made from scratch.)

If you're interested in how we record the data, you can view the spreadsheet here. The main weakness of the spreadsheet is that it relies on a ratings system, which is tough to calibrate and I think depends on our mood. Ideally, I'd like to switch to a pairwise comparison system, particularly for the taste rating. This might be difficult to implement though. Jenny is a great cook, and has been a great sport about entering meal data, but she is less of a good sport when I quiz her about whether she really prefers minestrone over sausage bean kale soup.

I plan on updating this as we get more data- follow me on twitter for a notification, or use the e-mail subscription on the right.

Sunday, February 7, 2016

Bills Introduced to Congress by Presidential Candidates

The visual above shows the total number of bills submitted to congress by current presidential candidates. Hillary Clinton has submitted the most bills, but only 3 out of 353 passed. Of the five candidates, Clinton also submitted the most bills per year during her congressional career- about 44 per year (353/8). Jon Kasich submitted the least number of bills per year- 68 during his 18 years, or less than four per year. He also had the most success passing his bills.

The legislative record of the democratic candidates is similar to the of Barack Obama- he was successful with two of his 275 bills.

Reading the text of the successful bills is just as embarrassing as the totals. Bernie Sanders has passed three bills, two of which renamed post-offices. His other bill is more serious- it ties increases in veterans benefits to cost of living adjustments for social security. Hillary renamed a post office, named a highway, and changed the designation of the Kate Mullany House in Troy NY from a historic landmark to a historic site.

On the republican side, Ted Cruz's one successful bill prevents people who previously committed terrorism against the United States from entering the country as a members of the United Nations. Marco Rubio's one law is more endearing, but also low impact- it declares it is US policy to encourage other countries to have birth registries, particularly for girls. This policy was advocated for by the United Nations Foundation (don't tell Cruz).

John Kasich has passed by far the most impactful legislation; as chairman of the the house budget he successfully introduced welfare reform in 1996, tax reform in 1997, and the balanced budget act in 1997.

The filters at the bottom can reveal additional information. For example, try searching "terrorism" to see who introduced the most bills on the subject. Or add resolutions to the type filter to see even more attempted legislation. (The default view only includes bills. Resolutions are usually less impactful, and most types are not intended to become law.)

The data above comes from, was extracted with, and visualized with Tableau. Follow me on twitter to see similar posts.

Saturday, January 23, 2016

Atlanta Home Prices

My previous post on Atlanta housing shows rental prices by neighborhood and their five-year trend. This post uses home price data from Zillow to look at an eighteen-year trend. I'll also explore the divide between southwest and northeast Atlanta and racial income gaps.

First, a map of home prices in Atlanta, as of November 2015. This map was created using price per square foot data from Zillow and multiplying to estimate the average price for a 2000 square foot home. Blank neighborhoods do not have data in the Zillow dataset.

As expected, the map looks similar to the apartment price map- neighborhoods with expensive homes tend to have expensive apartments. The graph below demonstrates this by graphing home prices against apartment prices. 

This graph is helpful for understanding the data set. Neighborhoods above the trend line, like Midtown and Downtown, have high rental prices relative to home prices. This could be because rental stock that is nicer than home stock, or because many homes in these neighborhoods are condominiums, and are less expensive on a price per square foot basis because they have condo fees and less land per resident than a traditional home.

The home price map also shows a striking divide between Northeast and Southwest Atlanta. The graph below investigates this by graphing the home price for the two halves of Atlanta. All prices are adjusted to 2015 prices using the CPI.

The Southwest rose by more on a percentage basis from 1998 to 2006- 62% compared to the Northeast's 38%. But home values in the Southwest then fell by 59% during and after the recession, while homes in the Northeast only fell by 31%. The Northeast homes are now only 8% below their pre-recession high, while Southwest homes are 57% below their pre-recession high.

The larger price swings in Southwest Atlanta were caused at least in part by federal programs. Both Presidents Clinton and Bush led programs designed to increase home ownership among low to middle income households, and Bush specifically targeted his program towards minorities. These programs increased prices in low-income neighborhoods by creating increased demand, and the lax lending rules put the neighborhoods at a greater risk during a recession. The less educated were also more likely to lose their jobs during the recession, compounding the problem.

The unintended consequences of the home-ownership programs is similar to the problems with affordable housing programs described in my previous post- they are well-intentioned programs designed to help the poor and middle class, but end up making the average person worse-off because they distort the market.

Back to Atlanta: The video below shows how each individual neighborhood changed from 1998 to 2015.

For those interested: click here for the interactive graph version of the above video. Or click here for the video (or graph) that shows growth to 2015 over time (instead of growth from 1998), which I think is less intuitive but more relevant.

Comparing Northeast and Southwest Atlanta raises the question of race- the Northeast half is mostly white, and the Southwest half is mostly black. The graph below shows median household income for blacks and whites in the city of Atlanta, as well as the Metro area and the country.

The income gap for the city of Atlanta is depressing. Blacks in Atlanta have noticeably lower incomes than the national average for blacks, while whites have higher incomes than the national average. This situation is unique to the city proper- in Atlanta's metropolitan statistical area, blacks have a higher income than the national average.

My last post led to interesting discussion on Atlanta Reddit and Curbed Atlanta. I also received an e-mail from Jarod Apperson on the relationship between gentrification and luxury construction:

Related to this topic, one thing I think could use more clarity is the relationship between luxury construction and gentrification.  If gentrification is defined as an area's mean income, rents, etc. rising from wealthier residents moving in, that can happen either through displacement, new construction, or some mix of the two.  Often displacement is what folks get most worried about.  It is concerning to think that people who have lived in a community for some time are not able to continue doing so because of changes happening around them.  In lamenting that new construction is expensive, the articles you point to seem to be misinterpreting the reality of new (luxury!) construction's relationship with displacment, which you hint at in point 4 on your list of takeaways.  
Michell Eloy at WABE: "But low- and middle-income renters – renters like Huftalen – say they feel increasingly squeezed by the market, unable to afford the new luxury apartments and edged out by stiff competition and equally high prices for older units."
The point Eloy fails to make is that were it not for new luxury apartments, the high prices for older units would have risen even more (more on that in a second).  
Editorial Board at CL: "But left unchecked, this environment could create a frightening affordability crisis where, years down the line, Atlanta is only a place for the well to do. That's how affordability crunches happen — developments get rolled out, the city's population grows — and boom — you're suddenly pushed out by property taxes and house-hunting in Riverdale."
No, that's not how affordability crunches happen.  New residential developments rolling out, do not make housing less affordable.  In fact, they do the opposite.  Rising residential demand from any number of factors (preference for less time in traffic, proximity to new amenities like the Beltline, proximity to new restaurants/stores etc.), leads to affordability crunches.  Meanwhile as new housing developments get rolled out, they ameliorate such crunches.
Rather than lamenting luxury construction, these writers should be championing luxury construction as a deterrent from the displacement they are so worried about.  The reason is this: by decreasing demand for older units, new luxury construction lowers rents for the existing housing stock.  The theory is simple.  When a new building opens, it attracts some residents from older places nearby and because there is less demand for their units, those places charge rents that are lower than they would be in the absence of this new construction (note that this doesn't mean rents necessarily go down at older places, they might go down sometimes, but they certianly end up lower than they would in the absence of new residential construction).
So, given this wrinkle, what really matters is changes in the distribution of rents, not changes in the mean rent.  It is entirely possible for mean rents to rise substantially without any displacement occurring as long as housing options aren't lost on the left side of the distribution.  
Indeed there is evidence of this phenomenon is occurring here in Atlanta.  A recent BisNow article reports, "While rents shot up another 10 cents/SF on average to $1.76/SF...same-unit rents actually slipped nearly 4% year-over-year."  So what is happening is this: new developments are opening at above-average rents (luxury units, raising the mean), and attracting at least some tenants who would have otherwise chosen nearby existing multifamily units.  As a result, those existing multifamily units are getting cheaper, lowering their prices to stay full.  In other words, not only is luxury construction not leading to displacement, it is actually preventing displacement.  It is keeping our city affordable.
It would be a shame to see a plan like this one derail luxury construction's role in keeping Atlanta affordable.  I worry that a misunderstanding of housing markets on the part of both the press and politicians may end up leading Atlanta toward less affordable housing, despite hopes for more.
Update (1/24/16): commenters on reddit point out that Atlanta had high levels of mortgage fraud before the recession, which inflated home values. This happened in both low-income and high-income neighborhoods. Lax lending rules intended to increase home ownership rates were partially responsible for this problem too.

Tuesday, January 12, 2016

Atlanta Rental Prices: A Tale of Two Cities

Neighborhoods in Old Fourth Ward have gone from abandoned to beautiful in a few short years. A beautiful park, apartments, and Ponce City Market exist in a space formerly occupied by warehouses, parking lots, and abandoned buildings. As this space and others have improved, the rents have rose, and several recent articles voice this concern.

My neighborhood in Kirkwood is great and far cheaper than where my sisters live in New York and DC, so I wanted to better understand calls for city hall to take action on affordable rents. I downloaded data on average apartment prices by neighborhood from Zillow to make this visual:

Mouse over the map to get price per square foot for each neighborhood, and the five year price change, adjusted for inflation (CPI). Blank neighborhoods are missing in the Zillow data.

Its true that there are a couple neighborhoods in Buckhead with median rent over $2 per square foot, and Midtown is up to $1.85 per square foot. But half the city can still be rented for less than $1 per square foot. My own neighborhood has a median rental price of $1.19 per square foot.

To better show change over time, the visual below shows current price graphed against the five year percentage change in prices.

The visual is striking. Although a price divide existed between the Southwest and Northeast halves of the city five years ago, almost every neighborhood in the Southwest half of the city has gotten less expensive, and every neighborhood in the Northeast half has gotten more expensive.

I have several take-aways from these graphs.

1. When people complain that the city is getting too expensive, they only mean the most desirable neighborhoods where they want to live. Half the city is very cheap.

2. Price is a good measure of desirable neighborhoods. The divide between nice neighborhoods and bad neighborhoods in Atlanta is growing.

3. Plans for affordable housing should be very careful. Most affordable housing plans actually make housing more expensive. Consider a policy that requires XX% of affordable housing per new development. Less total developments will be built because developments are now less profitable. Then, in the developments that are built, less units will be on the open market. Prices are then higher due to the policy because the housing supply is smaller. Good for the lucky few who win the affordable housing lottery, but bad for everyone else.

4. Atlanta should instead be very generous in encouraging and approving development. Increased housing supply will help keep down prices and allow more people to live where they desire.

5. Increased property tax from development can then help our poor neighborhoods improve. Luxury buildings, scary to some, generate property taxes that can be spent on improving schools, safety, and transit, or on more targeted development plans. Atlanta needs to increase investment in poor neighborhoods as property taxes rise. Luxury buildings also have residents who contribute to the economy and benefit local low-wage earners.

I'll publish another post on home price data from Zillow later this week. There are some differences from the apartment data, and more years. For a notification, use the google plus or e-mail widgets on the right, or follow me on twitter