The first section of the P1 file (Total Population and Race) for census blocks is now available from BACOG as a compressed (.zip) ArcGIS Shapefile.

You can view this file using free ArcGIS Explorer, Google Earth, or ArcGIS Desktop.  This shapefile has Census Block information for Cook, Lake, Kane, and McHenry Counties.

Click here to download the four-county shapefile (40.0 MB)

If you don’t need all four counties, click here to download an individual county.

The field name reference table is located at the link below on Page 64.
http://www.census.gov/prod/cen2010/doc/pl94-171.pdf

If you’re a municipality, state, county or congressional district, Census 2010 FactFinder 2 is a website that will work well to summarize the data in a simple table listing population and race counts.  However, when it comes to determining population for unincorporated areas, library districts, or large planning areas, like BACOG, we need to access the geographic data and the tabular data.  An easy way to do this is using GIS.

Step 1: Luckily, the retrieval of census block shapefiles (the geographic data layers that allow us to see the area) is pretty easy:

1. Visit the 2010 Census TIGER/Line Shapefiles site: http://www.census.gov/geo/www/tiger/tgrshp2010/tgrshp2010.html and click ‘Download Web Interface’.
2. Select ‘Blocks’ as the Layer Type and then pick your state and county.
3. Unzip the file that downloads.  Repeat for additional counties if needed.

Step 2: Downloading the tabular data

Accessing the tabular files and creating the GEOID field which is a required field to join Census Data to the TIGER/Line Shapefile, is a little more complicated.  Full documentation of the steps that include downloading data, an access shell, creating relationships between the tables, creating the GEOID query and more are located here: http://www.census.gov/rdo/pdf/0HowToUseMicrosoftAccessShells.pdf

While this is a good exercise in learning new file types and a few “ins and outs” of Access 2007, not all users have the software or time to manipulate this data.  The Department of Commerce has made their state-wide database available via FTP to BACOG and we have extracted block summary data for our four counties: Cook, Lake, Kane, and McHenry.  Please contact BACOG or download the data from the link above to access this information.