This dataset contains county population in Iowa from 1990 to the most current year available. Data from 1990, 2000, and 2010 comes from the decennial censuses while the years in between are produced annually. Caution is urged in making year-to-year comparisons of population estimates. When the Census Bureau releases new population estimates for the current year, it also revises estimates for previous years in the decade. Aggregating multiple years is discouraged.