Border irregularities of the United States


Border irregularities of the United States, particularly panhandles and highway incursions into other jurisdictions, are shown here. Often they are a result of borders which do not conform to geological features.

International

Canada

There are several exclaves between the United States and Canada, including the entire state of Alaska. Other exclaves include Akwesasne, the Northwest Angle, and Point Roberts.
The status of the waters around Nunez Rocks is disputed. Nunez Rocks is a low-tide elevation area that is south of a line known as the "A-B" Line, which was defined in a 1903 arbitration decision on the Alaska–Canada boundary. The court specified the initial boundary point at the northern end of Dixon Entrance and Point "B" to the east. Canada relies on the "A-B" Line as rendering nearly all of Dixon Entrance as Canadian internal waters. The U.S. does not recognize the "A-B" Line as an official boundary, instead regarding it as allocating sovereignty over the land masses within the Dixon Entrance, with Canada's land south of the line. The U.S. regards the waters as subject to international marine law, and in 1977 it defined an equidistant territorial sea throughout Dixon Entrance. This territory, which surrounds Nunez Rocks, extends south of the "A-B" line for the most part. The United States has not ratified the Law of the Sea Treaty, although it adheres to most of its principles as customary international law. Under the treaty, LTEs may be used as basepoints for a territorial sea, and the U.S. uses Nunez Rocks as a basepoint. As a non-signatory, however, there is nothing preventing the U.S. from claiming areas beyond the scope of the Law of the Sea Treaty. The fact remains that, for about half of each day, above-water territory that Canada regards as Canadian is surrounded by sea territory that the U.S. has declared to be American.
Another disputed area is the Grey Zone, including Machias Seal Island, in the Gulf of Maine.
The Aroostook Valley Country Club is a golf course which straddles the Canada–US border, between the U.S. state of Maine and the Canadian province of New Brunswick. The club, located near Perth-Andover, New Brunswick and Fort Fairfield, Maine, has its course and clubhouse on the Canadian side of the border and its parking lot and pro shop on the American side.
East Richford Slide Road in the U.S. state of Vermont crosses into the Canadian province of Québec for a distance of approximately 100 meters before returning to the United States.
The Piney Pinecreek Border Airport runway straddles the Canada–U.S. border, between the U.S. state of Minnesota and the Canadian province of Manitoba. When flying to this airport, you must call customs officials at least one hour prior to landing.

Mexico

In Texas and Mexico, shifts in the course of the lower Rio Grande have created numerous pene-exclaves. Under the Boundary Treaty of 1970 and earlier treaties, the United States and Mexico have maintained the actual course of the river as the international boundary, but both must approve proposed changes. From 1989 to 2009, there were 128 locations where the river changed course, causing land that had been on one side of the river to then occupy the opposite bank. Until the boundary is officially changed, there are 60 small pene-exclaves of the state of Texas now lying on the southern side of the river, as well as 68 such pene-exclaves of Mexico on the northern side of the river.

Russia

The legal status of the U.S.-Russian border is unclear. The United States Senate ratified a treaty setting the boundary with the Soviet Union in 1991. However, shortly after, the Soviet Union collapsed, and the Russian parliament never voted on the treaty.

Cuba

The boundary between the United States and Cuba is a maritime boundary along the Straits of Florida. Despite tense relations between the countries, the United States operates a military base in Cuba, Guantanamo Bay. The land on which this military base sits is not sovereign United States territory; rather, it is leased from the Cuban Government.

States and territories

Separated by the water

These border irregularities were caused by changes in the Mississippi River during the 1812 New Madrid earthquake or other river changes:
Other irregularities involving the Mississippi River:
Some highways are not connected to the rest of their nominal highway systems: