Mason City is the county seat for Cerro Gordo County in north central Iowa and is located approximately halfway between the capital cities of St Paul, Minnesota and Des Moines, Iowa. The area of the city is 28.1 square miles of incorporated land.
Mason City is accessible by Interstate 35 to the west and Interstate 27/18 to the south, which is also known as the Avenue of the Saints, and Highways 65 and 122 intersect in the center of the community.