Des Moines is the capital and the most populous city in the U.S. state of Iowa. It is also the county seat of Polk County. A small portion of the city extends into Warren County.[ It was incorporated on September 22, 1851, as Fort Des Moines which was shortened to "Des Moines" in 1857. It is named after the Des Moines River. Des Moines is a major center for the insurance industry and also has a sizable financial services and publishing business base. In fact, Des Moines was credited with the "number one spot for U.S. insurance companies" in a Business Wire article.