Washington, DC

ZIP code 20403 is located in Washington, DC, and is home to the United States Capitol, the iconic building where the U.S. Congress meets to conduct legislative affairs. The ZIP code also encompasses the Supreme Court of the United States, where the highest court in the nation convenes to interpret the Constitution and make legal decisions. Additionally, it includes the Library of Congress, the largest library in the world with millions of books, recordings, photographs, and manuscripts.