How is the Voting-Age Population constructed?
The voting-age population estimates are generated from the July 1 Census Bureau population estimates by age-sex-race. Estimates for an election month are constructed by linearly interpolating the change between the most approximate pair of estimates. For example, to estimate the Nov 2004 VAP population, add to the July 1, 2004 estimate the following: the July 1, 2004 estimate minus the July 1, 2003 estimate, divide by 12, and then multiply by 4. When forecasting, I adjust the most recent estimate in a similar manner. It should be emphasized that although these estimates are based on official Census Bureau reports, listed below, but they are not directly produced by the Census Bureau and should not be cited as a Census Bureau product.
