the Gulf of Mexico to the southeast. Alaska borders the Pacific Ocean to the south and southwest, the Bering Strait to the west, and the Arctic Ocean to the north, while Hawaii lies far to the southwest of the mainland in the Pacific Ocean. Forty-eight of the states are in the single region between Canada and Mexico; this group is referred to, with varying precision and formality, as the contiguous United States, and as the Lower 48. Alaska, which is included in the term continental United States, is located at the northwestern end of North America. The capital city, Washington, District of Columbia, is a federal district located on land donated by the state of Maryland. (Virginia had also donated land, but it was returned in 1849.) The United States also has overseas territories (Insular areas) with varying levels of autonomy and organization: in the Caribbean territories of Puerto Rico and the U.S. Virgin Islands (formerly the Danish Virgin Islands, purchased by the US at the beginning of WW2), and in the Pacific the inhabited territories of American Samoa, Guam and the Northern Mariana Islands, along with a number of uninhabited island territories. Some of the territories acquired were a part of United States imperialism, or to gain access to the east. Nearly all of the United States is in the northern hemisphere—the exceptions are American Samoa and Jarvis Island. Physiographic divisions The eastern United States has a varied topography. A broad, flat coastal plain lines the Atlantic and Gulf shores from the Texas-Mexico border to New York City, and includes the Florida peninsula. This broad coastal plain and barrier islands make up the widest and longest beaches in the United States, much of it composed of soft, white sands. The Florida Keys are a string of coral islands that reach the southernmost city on the United States mainland (Key West). Areas further inland feature rolling hills, mountains, a diverse collection of temperate and subtropical moist and wet forests. Parts of interior Florida and South Carolina are also home to sandhill communities. The Appalachian Mountains form a line of low mountains separating the eastern seaboard from the Great Lakes and the Mississippi Basin. New England features rocky seacoasts and rugged mountains with peaks up to 6200 feet and valleys dotted with rivers and streams. Offshore Islands dot the Atlantic and Gulf coasts. A recent global remote sensing analysis suggested that