This is a list of all tripoints in which the boundaries of three (and only three) U.S. states converge at a single geographic point. Of the 60 such points, 36 are on dry land and 24 are in water.[1] Of the points in water, 3 are in the Great Lakes and thus have no land nearby. A tripoint occurring in a populated area may also be informally described as a tri-state area.
Land
Connecticut–Massachusetts–New York tripoint marker
Tri-State Corner. Marker on dry land at surface level and unmarked on lake in cavern directly below. Stolen in 2009 and returned two years later.[3][4][5]
Unmarked on seasonal silt island or in river bed, but Oklahoma–Texas state line as revised in 2000 is defective in not extending from vegetation line on south bank to pre-established tripoint.
Brass marker with the shapes of the three states is located in a monument box beneath the surface of a rural road. Was set in 1999[20] and is referenced by a granite marker 20 feet to the east on the Michigan-Ohio line.[21]
True point is marked with a disc in the center of a T-shaped road intersection.[22] A witness monument nearby in the South Dakota corner acknowledges the tri-point being set in 1859.
La Crosse, Wisconsin metro area. Was apparently marked at one time with a sign that had been anchored in the location, but that sign has since been moved as of 2001.[37]
Unmarked, at high water mark, because the Maryland West Virginia state line is at the high water mark even tho the Maryland Virginia state line runs generally along the low water line, so perhaps misclassified here because it is rarely actually under water.[38]
Technically the Beginning Point of the U.S. Public Land Survey, although the actual monument is 1,112 feet north of the tripoint due to the tripoint's current location under water; Pittsburgh Tri-State.
^Graff, Bill (Summer 2006). "Sentinels at the Northern Border"(PDF). Unearthing New Jersey. 2 (2). New Jersey Geological Survey: 1–3. Tri-States Monument ... this small granite slab serves as both the northern end of our boundary with Pennsylvania and the northwestern end with New York.