Geographic Market Area

[Cory Haberkern]

Hi,

I asked this quite some time ago, and have reached out directly to opa...@philly.gov but have received no response.

Does the Geographic Market Area described in this map exist anywhere in the data? 

https://www.phila.gov/media/20220525080534/opa-tax-year-2023-reassessment-gma-map.pdf

I am looking for either the Point Geometries for the GMAs and/or their subcomponents or even just a mapping of parcel number to the sub GMA and broader GMA.

Thanks,

Cory

[Robert Cheetham]

Hi Cory. The Board of Revision of Taxes (perhaps before OPA was separated from it) used to maintain a data set of the GMA areas and there is a 2016 version available for shapefile download on PASDA at: https://www.pasda.psu.edu/uci/DataSummary.aspx?dataset=154 - I'm not sure why the City hasn't added an OpenDataPhilly catalog entry for this.

I haven't compared the 2021 map in that PDF, but I imagine it's potentially the same.

Best,

Robert

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[Cory Haberkern]

Hey Robert,

Thanks for the quick reply.  

I'm hesitant to use the 2016 version, as it probably wasn't used for the latest round of property assessments. I'll compare the two maps, but it's going to be difficult doing an "eye check" between the maps.

Do you know the best way to contact actual representatives from the City Government to get this data? Their official emails seem to be a black hole.

Thanks,

Cory

[Robert Cheetham]

Cory,

I think that's a reasonable assumption. From comparing the 2016 data to this 2021 version, it looks like at least E, F, G, and P have changed and at least Q and S are new.

I think you can take three paths:

 * Update the 2016 data yourself based on the PDF

 * Contact the open data team at ma...@phila.gov (https://www.phila.gov/programs/open-data-program/)

 * Request from OPA through the open records system: https://www.phila.gov/privacy/pdfs/finalcityopenrecords.pdf  The OPA's Open Records Officer is currently Drew Aldinger (but please note that this list of open records officers is regularly updated).

Best regards,

Robert

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[Cory Haberkern]

Thanks Robert,

Yeah I was able to pull up the map in Python and looks like there's some big changes.

The problem with updating the data from the map myself is that it doesn't seem to be possible! There is no tract -> GMA mapping, nor geometrics. Unless you're familiar with any python packages that can interpret PDF maps.

I can contact the Maps team, and reach out to Drew Aldringer. I appreciate those contacts!

Best,

Cory

[Robert Cheetham]

Hi Cory. My approach to editing would be to use ArcGIS or QGIS to reassign the sub-units to the appropriate GMAs. From visually viewing it, I don't think more than a couple of dozen sub-units have changed and they just need to be reassigned from one GMA letter to another. 

BTW, I don't think the sub-units are census tracts. I'm not sure how they were developed but they don't line up with census geometry.

Best,

Robert

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[Cory Haberkern]

Thanks, I'll try this out! 

I had assumed they were census tracts (or block groups) but they might be individually designed street blocks for Philly. Who knows!

I appreciate you help!

Best,

Cory