I am looking at census tract TIGER/Line shapefiles from data.gov (https://www.census.gov/cgi-bin/geo/shapefiles/index.php), and I see that they provide options for census tracts for different years.

I noticed that the file size between the census tracts for 2010, 2011, 2012,... 2017 all have different file sizes. I thought the census tract was supposed to only be updated per decade? I'm wondering why this is.

migrated from gis.stackexchange.com Jun 14 '18 at 9:14


  • If this is open data then the place to ask may be the Open Data Stack Exchange. – PolyGeo May 1 '18 at 10:03
  • Do the actual tracts change, or is it just the file sizes? – nmtoken May 1 '18 at 15:10
  • Not sure if the tracts themselves get adjusted between census years... the data within the tracts file doesn't contain anything that might get updated by the American Community Survey – mapBaker May 1 '18 at 17:47

You're correct in that census tracts only change, if at all, after an official U.S. Census, which only occurs once per decade.

It seems to me that the user interface on FactFinder obscures this fact by forcing you to select the year you're looking for before the granularity of geography. Although year to year census tracts do not change, it is possible that other geographic boundaries have changed year over year, such as, say, a city's geography changes because of annexation.

This is the reasoning behind selecting the year you are searching for; for those datasets that do change from year-to-year, it's helpful to select the year. But that doesn't mean the year is applicable to all geography types, including the Census Tracts.

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