Quadripoint
The Four Corners Monument is the only point in the United States where four states meet: Colorado, Utah, New Mexico, and Arizona meet at right angles. The United States first acquired the area now called Four Corners from Mexico after the Mexican–American War in 1848. In 1863 Congress created Arizona Territory from the western part of New Mexico Territory. The boundary was defined as a line running due south from the southwest corner of Colorado Territory, which had been created in 1861. By defining one boundary as starting at the corner of another Congress ensured the eventual creation of four states meeting at a point, regardless of the inevitable errors of boundary surveying. The monument is centered at .
8 Mile Corner
8 Mile Corner is a monument in the Cimarron National Grassland dedicated to the tri-point (a place where three states meet) of Kansas, Colorado, and Oklahoma. This point is also the meeting point for three distinct regions of America - the Western United States (Colorado), Midwestern United States (Kansas), and South Central United States (Oklahoma). The landmark is a windmill with the three states' abbreviated names on the blades. The windmill monument was built in 1903. In 1990, satellite images showed the actual meeting place to be several feet away from the monument. A brass plate in the ground marks this. The site is approximately west of Elkhart, Kansas on mostly unpaved State Line Road.