The domestication of maize ~10,000 years ago resulted in dramatic differentiation from its wild ancestor teosinte. Subsequently, maize spread rapidly across the Americas, adapting to a number of new environments. Beginning in the 20th century, maize has also been subjected to intensive artificial selection by breeders. Each of these periods of adaptation have left their mark on patterns of genetic diversity. I will discuss some of our recent work using population genetics to learn about the history and process of adaptation in maize.