What is the capital of the United States?

Washington, D.C. is the capital of the United States because it was established as the nation's capital in 1790. The choice of a specific location for the capital was a key compromise among the founding fathers, aimed at balancing the interests of both northern and southern states. Washington, D.C. was specifically chosen for its strategically central location along the Potomac River, making it accessible from both regions.

The city serves as the political heart of the nation, housing the federal government, including the President's residence (the White House), the Capitol building (home to Congress), and the Supreme Court. This geographical and political significance emphasizes the role of Washington, D.C. as not just a capital in name, but as a representation of the nation's governance. In contrast, the other cities listed do not serve as the federal hub and thus do not hold the title of capital.