ACS Data Users Group

Hello everyone,

I would like to identify block groups in the 5-Year ACS data (currently 2015-2019) according to whether or not they are on the nation’s coasts. Information in the Geographic Areas Reference Manual suggests that it is possible to do so. What would be the easiest way to obtain the relevant data (ideally without using GIS software, with which I am unfamiliar)?

These are the sources I’ve looked at:

• https://tigerweb.geo.census.gov/tigerwebmain/TIGERweb_state_based_files.html provides the land area and water area for block groups but does not identify the water type (and, from the Geographic Areas Reference Manual, it seems I would only be interested in coastal water and territorial sea water).
• https://www.census.gov/library/publications/2010/demo/p25-1139.html identifies counties as coastal but that is not granular enough for my project needs.

Thanks in advance for any advice!

Hi NT,

My understanding is that the numbering convention of the GEOID will tell you if it's a water tract or not, in that the first digit of water tracts is denoted by a 9. Pretty sure the water/non-water distinction is at the tract level, not the block group level (so all BGs within a water tract can be assumed to be water BGs).

So for example, in Delaware, a tract with the GEOID 10001990000 is a water tract. First two digits are the state FIPS (10, in this case), the next three digits are the county FIPS (001, in this case), and then the next 6 digits are the tract FIPS (990000). This tract's FIPS starts with 9, therefore it's a water tract. The GEOIDs for block groups will have additional digits at the end, but the tract that they are nested within will start with 9 if it's a water tract.

Hope this helps.

-Diana