Here's how that map of Baltimore property tax data was made - Technical.ly Baltimore

Dev

Dec. 17, 2014 10:33 am

Here’s how that map of Baltimore property tax data was made

The story behind a 2013 mapping project that's again making the rounds on social media.

"Lighter colors correspond to lower property tax values while darker colors indicate higher values."

(Via BmoreMapped)

Thanks to the wonders of social media and Reddit, a map that visualizes Baltimore City property tax data is getting a second round of sharing this week.

Ryan J. Smith created the map, which uses data from OpenBaltimore as its source, at the 2013 Hack for Change Baltimore hackathon. The map was initially at BmoreMapped.com, but the version that’s circulating today is at a new site. BmoreMapped should be back up within a couple days, Smith said.

Since it’s searchable and cuts across a wide segment of the population, it’s easy to see why there’s a lot of interest here. As one Redditor pointed out, the choice of blue color is also fitting for how property taxes make most of us feel.

With the renewed interest in the project, we thought we’d provide a little context on how Smith made the map.

See the map

Smith used property tax and address values stored in a table available at OpenBaltimore, as well as a table with geometry for each address.

“I used QGIS to handle the table join and initial visualization (colored polygons). This creates essentially a vector graphic that is georeferenced,” he said. “Then, using Mapbox, I layered this file with an OpenStreetMap view of Baltimore.”

On the map, darker colors indicate higher property tax values.

Before the hackathon, Smith said he had never worked with data from Baltimore’s portal before. He called the experience “great.”

“I was surprised at how easy it was to download all the relevant tables I needed. It really only took me an hour or two to download the datasets I needed and merge them,” he said via email. “Trying to use the site’s built-in queries and visualizations was a little slow and frustrating at the time, but being able to download a local copy of the data generally fixes that problem.”

Smith said he hopes the city continues to open up its data as much as possible. (New city CTO Jerome Mullen appears to share that opinion.) Smith initially wanted to include an additional layer on the map that showed property taxes actually paid, and a map that showed historic changes to property values. But at the time, that data wasn’t available.

Advertisement

“It could be accessed on a property-by-property basis through individual queries, but you were out of luck if you wanted to get this information for every property in the city,” he said. “As far as I know, wholesale access to assessment history data (say through SDAT) or property tax payment history (through the city’s page) is only achievable through screen scraping, which is against the terms of service of both sites.”

Hear that, open data advocates?

You must appreciate accurate, relevant and productive community journalism.  Support this sort of work from professional reporters with seasoned editors.  Become a Technical.ly member for $12 per month
Organizations: Hack the Change
Projects: OpenBaltimore
-30-
JOIN THE COMMUNITY, BECOME A MEMBER
Already a member? Sign in here

Advertisement

Track Maryland snow plows with the state’s web app: STORM

Google Maps is adding a feature that shows nearby Lime bikes and scooters

A new mapping effort will provide a closer look at the streams that feed the Chesapeake Bay

SPONSORED

Baltimore

Why a modern office matters for Asymmetrik’s growing culture

Baltimore, MD 21201

14 West

Business Analyst

Apply Now
Baltimore, MD 21201

14 West

Solutions Specialist

Apply Now
Baltimore, MD

SmartLogic

Developer

Apply Now

Boring Company map shows S. Paca St. as Baltimore terminus of ‘Loop’ tunnel

After police names disappear from court case search, Baltimore State’s Attorney candidate posts database

Here’s a map of water main breaks in Baltimore

SPONSORED

Baltimore

SmartLogic propels digital transformation aboard Baltimore Water Taxi

Baltimore, MD 21201

Agora Financial, an Agora Company

Front End Web Developer

Apply Now
Baltimore, MD 21201

Agora Financial

Email Deliverability Specialist

Apply Now
Annapolis Junction, MD

Asymmetrik

FULL-STACK DEVELOPER

Apply Now

Sign-up for daily news updates from Technical.ly Baltimore

Do NOT follow this link or you will be banned from the site!