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 .
Lake of the Woods County, Minnesota
The county contains the Northwest Angle, the northernmost point of the Lower 48 States, and the U.S. portion of Lake of the Woods, shared with Canada. The county also includes the exclave of Elm Point. Since Alaska has no counties, Lake of the Woods is the northernmost county in the United States. It is also the only county in the United States with four words in its name, although there is a parish in Louisiana called St. John the Baptist Parish, and the U.S. Census Bureau treats parishes as county equivalents for census purposes.