Those of us with an unfortunate need for Congressional district-level data know that it’s distressingly hard to track down. Historically, measures are available in the Decennial Census, but remain constant between redistricting cycles. (See Scott Adler’s data, for instance). Yearly measures are rare, partly because districts are purely political, as opposed to geographic, entities that are constantly drawn and redrawn.
The American Community Survey, the largest Census study available outside of the Decennial Census, was piloted in the late 1990s and implemented in 2005. It provides yearly demographic information for jurisdictions with as few as 65,000 residents; 5-year (and, until their discontinuation, 3-year) averages cover the rest. The macro-data (as opposed to individual micro-data, known as “PUMS”) contain district-level data. Harnessing the power of the ACS is a pain, however. The Census publishes over 1,000 ACS tables, and users of the slow and counter-intuitive FactFinder know how hard it is to find just the information they need; the imperative for longitudinal data multiplies the time spent tracking down, modifying, and downloading tables. If you want to skip the middle man of the Census’s lackluster data retrieval system, good luck! The ACS summary files are stored in thousands of unlabeled CSV files, with table data stored in randomized “sequence” files and coded with geographic indicators that are non-persistent between years and states. The “user tools” buried on the Census FTP server work only in SAS and are poorly documented.
I recently did the hard work of downloading and parsing the ACS One-Year Summary Files from 2005 to 2014. I have made the files, imported into Stata 14 and broken down by table subject, available here. Each file contains an id variable (which functions as a merge key, in case you want to concatenate the files), a year variable, a state postal code variable, a Congressional district variable (0 = state-level aggregations), and the table rows (table ID + a three digit number indicating the row’s position in the table) for each Census subject area.
—Clifford Vickrey, 5/1/16
United States Census Bureau. “Summary File.” American Community Survey. U.S. Census Bureau’s American Community Survey Office, 2016. Web. 1 May 2016 <http://ftp2.census.gov/>.