Adair is a city in Adair and Guthrie Counties in the state of Iowa. The Guthrie County portion of Adair is part of the Des Moines–West Des Moines Metropolitan Statistical Area. Its population at the 2000 census was 839.
Adair is recognizable from Interstate 80 by its tall yellow "smiley-face" water tower. Humorously known as "the happiest town on Earth", its roadsign greets visitors with, "Welcome to Adair; it'll make you smile".