Jefferson City, informally Jeff City, is the capital of the U.S. state of Missouri. It had a population of 43,228 at the 2020 United States census, ranking as the 16th most populous city in the state, but the 9th least populous U.S. state capital. It is also the county seat of Cole County and the principal city of the Jefferson City Metropolitan Statistical Area, the second-most-populous metropolitan area in Mid-Missouri and the fifth-most populous in the state. It forms part of the nine-county Columbia–Jefferson City–Moberly combined statistical area, which has 415,747 residents. Most of the city is located within Cole County, with a small northern section extending into adjacent Callaway County.