There are 5 US Post Offices in Adair County serving a total of 7,365 residents equating to 1,473 residents per post office. It's estimated that approximately 11,755 packages are handled across the 5 county post offices annually. Adair County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 7,682. Its county seat is Greenfield. The county used to be part of Iowa's 5th congressional district, which had a score of R+9 (strongly Republican) in the Cook Partisan Voting Index.