New York City is not the capital of the United States of America. Washington, D.C. is the capital of the United States, and as of 2014 has served in that capacity for over 200 years. The capital is known formally as the District of Columbia.
Washington, D.C. is named after George Washington, who picked the area for the capital and was the first President of the United States. The formation of the capital was made possible by land donated from Maryland and Virginia, and the initial land area was 100 square miles. D.C. had a population of 646,449 in 2013. The creation of a capital district was approved by the Residence Act on July 16, 1790.