Marshall County is a county located in the U.S. state of Kansas. Its county seat and largest city is Marysville. As of the 2020 census, the county population was 10,038. The county was named after Frank J. Marshall, a state representative who operated the first ferry over the Big Blue River.

Washington County is a county located in the U.S. state of Kansas. Its county seat and largest city is Washington. As of the 2020 census, the county population was 5,530. The county was named for George Washington, the 1st president of the United States.