The Constitution never mentions a Cabinet. It refers only to principal officers in each of the executive departments, whose written opinions the President may require. George Washington began meeting with his department heads as a group, and the practice became a fixture of American government. Congress created the departments one by one, often in response to national crises or new public demands, from westward expansion and industrialization to the Cold War and the September 11 attacks.
This guide groups the fifteen departments by era, explains what each does, and links to full entries on every department and its leaders.
From the 1950s to the 1970s, Congress built departments for the expanding federal role in health, housing, transportation, and energy. The Department of Health, Education, and Welfare, created in 1953, was later divided into Health and Human Services and a separate Department of Education, which opened in 1980. Housing and Urban Development followed in 1965, Transportation in 1966, and Energy in 1977 after the oil crises. In 2025 the administration moved to wind down the Department of Education, which only Congress can formally abolish, prompting legal challenges.
Departments are created, renamed, merged, and occasionally abolished by Congress. The Post Office Department, a Cabinet department for nearly two centuries, became the independent U.S. Postal Service in 1971. Presidents once had authority to reorganize agencies through plans subject to congressional veto, but that authority lapsed in 1984, so major changes now require legislation. In 2025 an executive order authorized Department of War as a secondary name for the Department of Defense, and the administration pursued large workforce reductions across many departments.
The Cabinet is the group of department heads and senior officials who advise the President. Its formal membership is the fifteen department heads and the Vice President, and Presidents often add cabinet-level officials such as the White House chief of staff, the director of the Office of Management and Budget, the U.S. Trade Representative, and the ambassador to the United Nations. Each department head is confirmed by the Senate and supported by deputy secretaries, under secretaries, and thousands of political appointees listed in the Plum Book.
The First Congress created three departments in 1789, State for foreign affairs, Treasury for finance, and War for the Army, along with the office of Attorney General. The War Department and the Navy Department, added in 1798, were merged after World War II into what became the Department of Defense in 1949, and the Attorney General gained a full Department of Justice in 1870. These four remain the senior departments and come first in the line of succession.
As the country expanded and industrialized, Congress created departments for new national concerns. Interior, created in 1849, took over public lands, Indian affairs, and later national parks. Agriculture, founded in 1862 and raised to Cabinet rank in 1889, served a nation that was still mostly rural. A combined Department of Commerce and Labor, created in 1903, split in 1913 into separate Commerce and Labor departments, reflecting the growing weight of business and organized workers.
The Veterans Administration, an independent agency since 1930, became the Department of Veterans Affairs in 1989, now one of the largest federal employers through its hospital system. After the September 11 attacks, the Homeland Security Act of 2002 merged 22 agencies, including the Coast Guard, the Secret Service, FEMA, and the immigration services, into the Department of Homeland Security, the largest reorganization of the government since 1947.
Departments are only part of the executive branch. Compare them with the agencies that sit outside them in independent agencies vs. departments, meet the people who run them in who's who: offices and titles, or step back to the three branches.