The crossword solution for the term DES ___, IOWA is MOINES. Des Moines is the capital and most populous city in the U.S. state of Iowa. It is also the county seat of Polk County. The city lies on both banks of the Des Moines River, which is a tributary of the Mississippi River. Des Moines is the economic and cultural hub of the state and is home to many businesses, universities, and other attractions.