High Quality Content by WIKIPEDIA articles! Stafford County (standard abbreviation: SF) is a county located in the U.S. state of Kansas. As of the 2010 census, the county population was 4,437. Its county seat is St. John. The county is named in memory of Lewis Stafford, captain of Company E, First Kansas Infantry, who was killed at the Battle of Young`s Point, Madison Parrish, Louisiana, June 7, 1863.