8 Mile Corner, Survey marker sculpture at state borders intersection, Oklahoma, United States

8 Mile Corner is a survey marker located at the exact point where the borders of Kansas, Colorado, and Oklahoma meet. The site sits beneath road level and is protected by a steel cover inscribed with official boundary markers.

The 1903 date belongs to the old mock weather vane, locally called a "windmill", not to the survey marker. The tri-point corner was reestablished in 1990 by the Bureau of Land Management, which set a cadastral survey disk in concrete below grade. The fallen wind vane was replaced by a new weather vane with a bison silhouette, announced on January 5, 2024, and the U.S. Forest Service and the State of Kansas added a sign that year.

The site's name comes from its distance: about 8 miles west of Elkhart, Kansas, along mostly unpaved State Line Road. A nearby 1990 BLM survey marker reads "Southwest corner of Kansas" above an arrow and "73.98 feet" below it, pointing toward the tri-point. The corner also joins three US regions: Colorado in the West, Kansas in the Midwest and Oklahoma in the South.

The site is difficult to access since it lies beneath the road and is normally covered by a steel plate. Visitors should contact the road departments of the involved states beforehand to arrange access to the marker.

A second BLM marker stands a short distance from the corner, its arrow labelled "Southwest corner of Kansas" with "73.98 feet" beneath it, giving the exact distance to the tri-point. The 1903 monument locals called the "windmill" was a mock weather vane, not the survey point itself; it fell and was replaced by a new bison-topped vane announced on 5 January 2024.