ACS Data Users Group

Hello,

I am glad to have landed here. Speaking in the context of state or county level.

What is the comprehensive definitive answer to "Why dont my shapefile tracts match other shapefile tracts?" Repeat the question for block group shapefiles. I have retrieved the GIS files from The state or the Tiger/Shapefile page of census.gov.

Who are the authoritative sources to tract and or blockgroup shapefiles? Tiger shapefiles vs Other shapefiles, isnt there one location I can get the GIS files?

Is there development on the geographies (tracts, block groups) by the census after release?

Thank you so much.

Can you specify what you mean by "other shapefile tracts"? Do you mean tracts provided from other sources, or TIGER data from different years, or something else?

If you are using 2020 data, but have downloaded 2019 geographies - or vice versa - (especialliy, tracts, block groups and blocks) they will probably not join. The core geographies of Census Bureau are reconfigured every 10 years to accommodate Decennial Census changes. So make sure if you download 2020 shapefiles, to download 2020 data, etc.

If you need help or guidance with this, please feel free to contact me at my census email - I'm there to help people with issues like these.

David Kraiker

Data Dissemination (and GIS) Specialist

david.j.kraiker@census.gov

As Mara said lots of reasons they might not match but you have the definitive National source. A county or any other entity storing shapefiles might keep them in a different projection, might simplify them or clip them to water bodies to make them look better or load faster in some context or might just be outdated.