The Iowa State Data Center is a great place to search for Iowa-focused data on: employment/unemployment, health, housing, income, language, population, poverty, race.
Iowa data is reported at the state, county, or in some cases metropolitan area/city/town level.
State-by-state comparisons are available for many variable.
Data ranges often cover ten to fifteen year spans (e.g. from 2005 to 2016).
County Quick Facts provide population data from 1850 to 2017 as well as current data on age, characteristics of commute to work, disabilities, educational attainment, ethnicity/ancestry, gender, household size, income, occupation (by general category), poverty rates, race, unemployment rates, and veteran status for each county in Iowa.
City Quick Facts (same as above - but for hundreds of Iowa towns and cities).
American FactFinder is the powerful demographic database from the U.S. Census Bureau. American FactFinder will provide data on total population as well as distributions for characteristics such as age, race, gender, education attainment, housing, veteran status, disability status, citizenship status.
County data can be quickly accessed via Community Facts (2017 Population Estimates, 2016 American Community Survey, and both the 2010 and 2000 Census).
Statistical Abstract of the U.S. is a commercial database that provides a wide range of demographic and economic national data.
State-by-state comparisons can be found by:
It is possible search earlier editions or all editions of this database (2013-2017) by changing the Select edition option on the first page of this database.
Statistical Abstracts of the United States were treasure troves of statistics (once made freely available by the U.S. Government).
Statistical Abstracts are still great one-stop resource for historic statistics - however - only some of the tables provide state-by-state information (some metropolitan area stats but data at the county level).