Four Corners Monument
The Four Corners Monument marks the quadripoint in the Southwestern United States where the states of Arizona, Colorado, New Mexico, and Utah meet. It is the only point in the United States shared by four states, leading to the area being named the Four Corners region. The monument also marks the boundary between two semi-autonomous Native American governments, the Navajo Nation, which maintains the monument as a tourist attraction, and the Ute Mountain Ute Tribe Reservation.
East Coast of the United States
The fourteen states that have a shoreline on the Atlantic Ocean are, from north to south, the U.S. states of Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia, and Florida. In addition, Pennsylvania and the District of Columbia border tidal arms of the Atlantic (the Delaware River and the Potomac River, respectively). The states of Alabama, Mississippi, Louisiana, and Texas, (via the Gulf of Mexico) as well as the territories of Puerto Rico, the US Virgin Islands, and Navassa Island (the latter only bordering the Caribbean Sea) have Atlantic coastline, but are not included in the definition.