Readme for Census Population Estimates
Brendan Price
July 30, 2014

This folder contains data from the Census Population Estimates. Where possible, it's best to use "intercensal estimates" (which incorporate known baseline populations at the start and end of the decade). These intercensal estimates are essentially computed by starting with the baseline population at the start of the decade, using data on births, deaths, and migration to estimate annual population in the years that follow, and then scaling these changes up or down as needed so that the end-of-decade estimates coincide with the actual Census count. For post-2010 years, I necessarily rely on "post-censal" estimates (which incorporate the baseline population only at the start of the decade).

Specifically:

For data from 1990-1999:
- I use the official intercensal estimates.
- Files available at http://www.census.gov/popest/data/intercensal/st-co/characteristics.html (separate file for each year).
- Codebook file at http://www.census.gov/popest/data/intercensal/st-co/files/STCH-Intercensal_layout.txt.

For data from 2000-2010:
- I use the official intercensal estimates.
- File available at https://www.census.gov/popest/data/intercensal/county/CO-EST00INT-alldata.html (separate file for each state).
- See the codebook file "https://www.census.gov/popest/data/intercensal/county/files/CO-EST00INT-ALLDATA.pdf".

For data from 2010-2012:
- I use the Vintage 2012 estimates (which are the most recent available as of this date). These are postcensal estimates.
- File available at https://www.census.gov/popest/data/counties/asrh/2012/CC-EST2012-ALLDATA.html (specifically https://www.census.gov/popest/data/counties/asrh/2012/files/CC-EST2012-ALLDATA.csv).
- See the codebook file "https://www.census.gov/popest/data/counties/asrh/2012/files/CC-EST2012-ALLDATA.pdf" to decode age groups, etc.

Because the underlying source files are quite large, we provide only cleaned population estimates at the commuting zone level. We provide these population data solely for the purpose of facilitating replication of the present paper. If you wish to use the Census Population Estimates in your own research, please download fresh extracts to ensure that you have the latest version of the data.