Washington, D.C., formally the District of Columbia and commonly referred to as Washington or D.C., is the capital of the United States of America. Founded after the American Revolution as the seat of government of the newly independent country, Washington was named after George Washington, first President of the United States and Founding Father. Washington is the principal city of the Washington metropolitan area, which has a population of 6,131,977. Washington has been described as an important political capital, owing to its status as the seat of the United States federal government. Washington is one of the most visited cities in the world, with more than 20 million annual tourists.

What's the best answer to this question: is washington dc considered part of the united states?
yes