United States

The United States of America is a federal constitutional republic comprising over sixty different districts. The country is situated almost entirely in the western hemisphere: its forty-eight contiguous states and Washington, D.C., the capital district, lie in central North America between the Pacific and Atlantic Oceans, bordered by Canada to the north and Mexico to the south; the state of Alaska is in the northwest of the continent with Canada to its east, and the state of Hawaii is in the mid-Pacific. U.S. territories, or insular areas, are scattered around the Caribbean and Pacific. As of the present, it has the third largest population on Earth, and the largest economy on Earth.

United Nations
It is supposed that New York City in the state of New York is the location of the supreme United Nations headquarters, commanding the UNSC Defense Force, Colonial Administration Authority, and the Colonial Military Administration as it was currently based there in the 21st century. However HIGHCOM, the High Command on the UNSCDF is based in Sydney, Australia. It may have been reorganized upon the formation of the United Earth Government into the United Republic of North America.

United Nations Space Command
The UNSC probably has hundreds of bases in the United States. One such facility is the ONI Chawla Base in Boston, Massachusetts. Although, many more have been mentioned.

United Republic of North America
The United States, along with Canada, Cuba and Mexico, have formed the United Republic of North America. However, the time of the formation is currently unknown.

Locations Of Note

 * Chawla Base in Boston was an ONI-controlled and directed UNSC base that held the Deep-Space Artifact the Covenant were after.
 * Cleveland was one of the locations attacked by the Covenant in the Second Battle of Earth.
 * Tactical Autonomous Robotic Defense System Testing Facility in Chicago, Illinois, which forms the Multiplayer level Foundation of Halo 2
 * New York is an important location on one of the ILB stories and it also home to some of the main characters.
 * Sergeant Avery Johnson grew up in Chicago.

Trivia

 * It is unknown if the USA still exists in the Halo Universe, as many other countries, and possibly the US itself, have undergone radical change, both politically and territorially. The USA is never specifically mentioned in any Halo canon, only cities and areas in it, though the term "American" is used. This may suggest it still exists.

Internal

 * Earth
 * UNSC
 * Boston
 * Continental Marines
 * United States Marine Corps

External

 * http://en.wikipedia.org/wiki/US