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Working with ZIP code data (and alternatives to using sketchy ZIP code data)

December 17, 2014 / / 5 Comments
1711 North Kimball Avenue, built 1890

This building at 1711 N Kimball no longer receives mail and the local mail carrier would mark it as vacant. After a minimum length of time the address will appear in the United States Postal Service’s vacancy dataset, provided by the federal Department of Housing and Urban Development. Photo: Gabriel X. Michael.

Working with accurate ZIP code data in your geographic publication (website or report) or demographic analysis can be problematic. The most accurate dataset – perhaps the only one that could be called reliably accurate – is one that you purchase from one of the United States Postal Service’s (USPS) authorized resellers. If you want to skip the introduction on what ZIP codes really represent, jump to “ZIP-code related datasets”.

Understanding what ZIP codes are

In other words the post office’s ZIP code data, which they use to deliver mail and not to locate people like your publication or analysis, is not free. It is also, unbeknownst to many, a dataset that lists mail carrier routes. It’s not a boundary or polygon, although many of the authorized resellers transform it into a boundary so buyers can geocode the location of their customers (retail companies might use this for customer tracking and profiling, and petition-creating websites for determining your elected officials).

The Census Bureau has its own issues using ZIP code data. For one, the ZIP code data changes as routes change and as delivery points change. Census boundaries needs to stay somewhat constant to be able to compare geographies over time, and Census tracts stay the same for a period of 10 years (between the decennial surveys).

Understanding that ZIP codes are well known (everybody has one and everybody knows theirs) and that it would be useful to present data on that level, the Bureau created “ZIP Code Tabulation Areas” (ZCTA) for the 2000 Census. They’re a collection of Census tracts that resemble a ZIP code’s area (they also often share the same 5-digit identifiers). The ZCTA and an area representing a ZIP code have a lot of overlap and can share much of the same space. ZCTA data is freely downloadable from the Census Bureau’s TIGER shapefiles website.

There’s a good discussion about what ZIP codes are and aren’t on the GIS StackExchange.

Chicago example of the problem

Here’s a real world example of the kinds of problems that ZIP code data availability and comprehension: Those working on the Chicago Health Atlas have run into this problem where they were using two different datasets: ZCTA from the Census Bureau and ZIP codes as prepared by the City of Chicago and published on their open data portal. Their solution, which is really a stopgap measure and needs further review not just by those involved in the app but by a diverse group of data experts, was to add a disclaimer that they use ZCTAs instead of the USPS’s ZIP code data.

ZIP-code related datasets

Fast forward to why I’m telling you all of this: The U.S. Department of Housing and Urban Development (HUD) has two ZIP-code based datasets that may prove useful to mappers and researchers.

1. ZIP code crosswalk files

This is a collection of eight datasets that link a level of Census geography to ZIP codes (and the reverse). The most useful to me is ZIP to Census tract. This dataset tells you in which ZIP code a Census tract lies (including if it spans multiple ZIP codes). HUD is using data from the USPS to create this.

The dataset is documented well on their website and updated quarterly, going back to 2010. The most recent file comes as a 12 MB Excel spreadsheet.

2. Vacant addresses

The USPS employs thousands of mail carriers to delivery things to the millions of households across the country, and they keep track of when the mail carrier cannot delivery something because no one lives in the apartment or house anymore. The address vacancy data tells you the following characteristics at the Census tract level:

  • total number of addresses the USPS knows about
  • number of addresses on urban routes to which the mail carrier hasn’t been able to delivery for 90 days and longer
  • “no-stat” addresses: undeliverable rural addresses, places under construction, urban addresses unlikely to be active

You must register to download the vacant addresses data and be a governmental entity or non-profit organization*, per the agreement** HUD has with USPS. Learn more and download the vacancy data which they update quarterly.

Tina Fassett Smith is a researcher at DePaul University’s Institute of Housing Studies and reviewed part of this blog post. She stresses to readers to ignore the “no-stat” addresses in the USPS’s vacancy dataset. She said that research by her and her colleagues at the IHS concluded this section of the data is unreliable. Tina also said that the methodology mail carriers use to identify vacant addresses and places under change (construction or demolition) isn’t made public and that mail carriers have an incentive to collect the data instead of being compensated normally. Tina further explained the issues with no-stat.

We have seen instances of a relationship between the number of P.O. boxes (i.e., the presence of a post office) and the number of no-stats in an area. This is one reason we took it off of the IHS Data Portal. We have not found it to be a useful data set for better understanding neighborhoods or housing markets.

The Institute of Housing Studies provides vacancy data on their portal for those who don’t want to bother with the HUD sign-up process to obtain it.

* It appears that HUD doesn’t verify your eligibility.

** This agreement also states that one can only use the vacancy data for the “stated purpose”: “measuring and forecasting neighborhood changes, assessing neighborhood needs, and measuring/assessing the various HUD programs in which Users are involved”.

The City of Chicago should implement filtered permeability immediately at Green Street and Milwaukee Avenue

November 21, 2014 / / 2 Comments
This is not a bikeable block

The multiple threats to bicyclists, to pedestrians, and to motorists, are pervasive in the depicted scene. There is low visibility for turning motorists which in turn causes them to encroach on the right of way of other street users, including other motorists, bicyclists, and pedestrians.

This single image shows everything that is inefficient and dangerous to bicyclists and motorists about the intersection between north-south Green Street and diagonal Milwaukee Avenue in River West. Motorists should be physically blocked from entering or exiting Green Street at this point because of the danger inherent in the current intersection design. The block of Green Street south of Milwaukee Avenue is so insignificant to the driving network that no other design intervention should be implemented.

The situation depicted in this photograph demonstrates why the City should implement filtered permeability and close this entrance of the Green Street/Milwaukee Avenue intersection to motor vehicle movement. While motorists would be barred from entering or exiting Green Street here bicyclists would still have access to Green Street as part of the low-stress bicycling network of which Green Street is a part, between Milwaukee and Van Buren Street in Greektown.

I first wrote about this problematic intersection in June on Streetsblog Chicago and it remains an issue. One of the two motor vehicles ahead is blocking part of the bike lane while the second threatens to enter it. The bus on the left prevents the bicyclist in the bike lane from maneuvering around either vehicle. The photo below shows the situation from a different angle, that of the motorist wanting to turn left.

The vehicle operator on the left – a bus driver, in this case – has stopped the vehicle because they can occupy the intersection with the vehicle, or leave it open. Essentially, the bus driver has stopped to “let” the motorists on Green Street proceed across Milwaukee and further north into Green Street or turn left onto Milwaukee. Their movements would, again, put the bicyclist in danger, and put themselves and other motorists in danger because they are making nearly-blind turns into faster moving traffic.

The threats to the motorist are as limitless as the ones to the bicyclist (although the bicyclist will experience much greater injury if the threat is realized). As the motorist is paying attention to other motor vehicle traffic the bicyclist is coming down this bike lane – yep, I took the photograph – and is additionally obscured by the line of parked cars on the bicyclist’s right, and is in the shadow of the bus and the buildings. It’s like there’s a perfect storm of blind spots.

The quickest way to implement a system of filtered permeability and raise the significance and safety of the Green Street and intersecting Milwaukee Avenue blocks within the low-stress bicycling network would be to install a series of large planter boxes that prevent motorists from entering or exiting Green Street but allow bicyclists to filter through the planters.

And skip any traffic impact study. Not a single parking space will be lost or be made inaccessible with the implementation. A traffic study is not an experiment, but has practically been a foreboding document that has only ever said “things will be different”. (A good plenty of them have also suggested adding multiple $300,000 traffic signals.)

I read on Streetsblog USA recently about Pittsburgh’s new protected bike lanes:

“Instead of asking people to judge the unknown, the city’s leaders built something new and have proceded to let the public vet the idea once it’s already on the ground.”

Chicago maintains a Silver bike-friendly commenting ranking, yet my initial analysis shows that our metrics are below average among other Silver communities after which I’m led to believe we’re undeserving of the medal. Safety is a citizen’s number one concern when considering to use a bicycle for transportation and it will take an expansion of the low-stress bicycling network – currently not a priority – to deserve the current ranking or achieve anything higher.

Two bicyclists take different routes around this driver blocking the bike lane with their car

This photograph depicts a nearly identical situation but from the perspective of the motorist on Green Street approaching Milwaukee Avenue. Two bicyclists have taken two routes around the motorist blocking the bike lane with their vehicle.

Proposed residential high-rise injects TOD and population loss into Logan Square conversation

October 31, 2014 / / 0 Comments
A public notice stands in front of an affected property

There used to be a Max Gerber plumbing supply store here that the absent landlord demolished to reduce his property taxes. A developer has proposed built 254 units in two towers here, in spitting distance from the CTA’s 24-hour Blue Line.

Developer Rob Buono has proposed two towers for a vacant property 400 feet away (walking distance) from the Chicago Transit Authority’s California Blue Line station. It has caused quite a stir in Logan Square about how much development is the right amount, and brings into question residents’ understanding of how the neighborhood demographics have changed.

It has also brought “TOD” into the local conversation. Buono will get some relief from exceptional car parking requirements because of the land’s proximity to the ‘L’ rapid transit station.

The process will be a long one. The first meeting, called by Alderman Moreno, was held on Thursday night. I counted over 70 people on the sign-in sheet when I came in, and many people arrive after so saying 100 people were there isn’t a stretch. Moreno described his development policy: whenever they need a zoning change they must present their proposal to the community so Moreno can get their feedback.

Before Buono spoke, though, Moreno asked Daniel Hertz to briefly talk about transit-oriented development and why the development (or at least the number of units and car parking spaces it proposes) is a good project for this place, and in this neighborhood. In balancing concerns about car traffic, keeping people close to the services and products they need, and making it easy to get around, it makes the most sense to put the highest number of housing units in close proximity to high-capacity transit versus anywhere else.

Essentially, Logan Square has lost residents – 10,000 people since 2000 – concentrating the burden of patronizing local businesses, seen as a distinguishing asset in the neighborhood, on fewer people. Additionally, adding housing is the best way to combat rising home prices (and unaffordable rents) by offering more supply which reduces demand on richer people buying, converting, or tearing down existing buildings.

While no building permits will be issued for the towers until Ald. Moreno, Plan Commission, and City Council approve the zoning change, you can track what other kinds of buildings developers are building in the area surrounding 2293 N Milwaukee on Chicago Cityscape.

You’ll see quickly that a majority of the projects permitted this year are for single-family houses. Some of these are built on vacant parcels while at least one is  being built where there was previously a multi-family house.

In 2014, within 1/8 mile of the site:

  • +0 units in multi-unit buildings
  • -1 deconversion, turning two units into one unit
  • -1 teardown, turning a two-unit property into a single-family property
  • +17 single-familiy homes
  • Net gain of a maximum of 15 units

At this rate, Logan Square may grow at an extremely low rate – these homes will likely be filled with small families. The decreasing household size is another factor in Logan Square’s population loss.

Read about people’s reactions to the towers on other sites:

Joe Moreno

1st Ward Alderman Proco “Joe” Moreno gracefully – given the circumstances – moderates the meeting.

I’ve got property tax data for Chicago Cityscape

September 28, 2014 / / 0 Comments
Wrigley Field Ahead of a Seemingless Meaningless Game, September 2011

Wrigley Field is an old baseball stadium in Chicago’s Lakeview neighborhood. Photo by Dan X. O’Neil

1. Licensed Chicago Contractors, my website that tracks what developers and the city are proposing to build or demolish in your neighborhood, is now called Chicago Cityscape.

2. I’m grateful to Ian Dees who helped me get property tax data for 2009-2013 for over 1.4 million PINs (property identification numbers) in Cook County.

I’m going through various parts of the property tax data and figuring out how to integrate it with Chicago Cityscape. The first time Ian got the data I found out I didn’t tell him to get the right PINs. I think I’ve fixed that now.

As part of this process I’m checking properties somewhat randomly, based on the permits I’m browsing. I most recently viewed a Wrigley Field building permit at 1060 W Addison Street – for a Zac Brown concert – so I searched its PIN and how much the property is “worth”. Here goes:

Year Amount Billed Assessed Value
2013 $1,517,665.09 $8,049,996
2012 1,498,971.03 8,049,996
2011 1,493,002.47 8,865,636
2010 1,489,160.89 8,865,636
2009 1,360,673.45 10,613,423

Notice how the assessed value dropped over $2 million from 2009 to 2010. And even though it had three unique assessed values, the annually changing tax rate adjusted the amount billed. You can see this information on the Cook County Property Info portal.

The Chicago Way: Potholes that definitely no longer exist

September 10, 2014 / / 2 Comments
311 report for a pothole

Screenshot of the 311 service tracker that tells me that the photograph I submitted contains no image of potholes.

The Chicago Way is as much about the process as it is about the result. This story involves what happens when you can’t provide accurate information about a street inspection in the tracking system that has been built, effectively making a group of potholes disappear.

I submitted a pothole report via the Chicago open 311 system – assigning it service request #13-00420100 – on April 12, 2013 for 1653 N Milwaukee Avenue near Red Hen Bakery and Athletico. Three days later the inspection found no potholes and the request was closed.

The website or the Chicago 311 system seemingly could not provide a better answer. Certainly dismissing the existence of potholes is the wrong response. There’s no hope for the future in this response. Maybe there’s a plan to resurface this block. This could be the opportunity to inform a concerned citizen. Instead, the response told me I’m wrong.

Fast forward to now and the situation has devolved. Potholes have gotten a little bigger and they’ve spread as if the street is diseased. What also sucks is that this problem will probably persist for at least another year from my report (unit April 2015) because the hot asphalt plants are going to shutdown soon.

This reminds me of that Chicago maxim: “We don’t want nobody that nobody sent.” Or Metra, that the trains would be on time if they didn’t have to stop to pick up passengers.

#TheChicagoWay

Potholes on Milwaukee Avenue - I reported them over a year ago

The potholes as of August 2014.