The Departments of State, Treasury, and Defense are the three oldest and most influential executive departments in the U.S. federal government. State runs foreign policy, Treasury manages the government’s money, and Defense oversees the armed forces. Their Secretaries hold the top three cabinet slots in the presidential line of succession, ranking fourth, fifth, and sixth overall.
What the Department of State Does
State is the lead federal agency on foreign affairs and the oldest executive department in the country. Congress created the Department of Foreign Affairs on July 27, 1789, months after George Washington’s inauguration, and renamed it the Department of State that September. The Secretary of State serves as the President’s principal foreign policy advisor and directs a worldwide network of more than 250 embassies, consulates, and diplomatic missions.1U.S. Department of State. Department Organization
The department’s day-to-day work includes negotiating treaties, coordinating trade and security agreements, and representing the United States at the United Nations.2USAGov. U.S. Department of State It also provides direct services to American citizens, most visibly through passport and visa processing, and it issues travel advisories for every country. State manages the Foreign Service, the specialized workforce of diplomats and support staff posted around the globe.
What the Department of the Treasury Does
Created on September 2, 1789, Treasury oversees the financial infrastructure of the federal government. The Secretary of the Treasury shapes domestic and international economic policy, manages the public debt, and acts as the government’s financial agent.3U.S. Department of the Treasury. Duties and Functions FAQs Almost every dollar the government collects or spends passes through the department in some form.
Revenue collection falls to the Internal Revenue Service, the Treasury bureau most Americans deal with directly. The IRS processed more than 161 million individual income tax returns during fiscal year 2024.4Internal Revenue Service. IRS Data Book 2024 Treasury also produces the nation’s money through two separate agencies: the Bureau of Engraving and Printing handles all paper currency, and the United States Mint manufactures circulating coins.5Bureau of Engraving and Printing. FAQs
Beyond revenue and currency, Treasury regulates national banks through the Office of the Comptroller of the Currency and finances government operations by issuing Treasury bonds and notes. The Secretary regularly advises the President on fiscal policy and international finance.
What the Department of Defense Does
The Department of Defense is the nation’s largest employer and the organizational backbone of American military power. Headquartered at the Pentagon in Arlington, Virginia, it employs roughly 1.4 million active-duty service members alongside hundreds of thousands of civilian personnel and reserve forces.6Performance.gov. Department of Defense The National Security Act of 1947 formally established the department, unifying the previously separate Departments of War and Navy under a single civilian leader.
The DoD oversees six military branches: the Army, Navy, Air Force, Marine Corps, Space Force, and, during wartime or by presidential direction, the Coast Guard. Space Force is the newest branch, established on December 20, 2019, and is the first new branch of the armed services created since 1947.7U.S. Space Force. About Us
Civilian control of the military is a foundational principle here. The Secretary of Defense is a civilian appointed by the President who exercises authority and control over all defense operations.6Performance.gov. Department of Defense The arrangement keeps the armed forces accountable to elected officials rather than concentrating power within military leadership. The annual defense budget regularly exceeds $800 billion.
Why These Three Rank Highest in the Cabinet
Under federal law, if both the President and Vice President cannot serve, power passes first to the Speaker of the House, then to the President pro tempore of the Senate, and then to cabinet secretaries in the order their departments were created. Because State, Treasury, and Defense are the three oldest, their Secretaries lead the cabinet portion of the line: State is fourth, Treasury is fifth, and Defense is sixth.8Office of the Law Revision Counsel. 3 USC 19 – Vacancy in Offices of Both President and Vice President
Not every secretary automatically qualifies. To be eligible, the officer must meet the constitutional requirements for the presidency: natural-born citizenship, at least 35 years old, and a resident of the United States for at least 14 years. The officer must also have been confirmed by the Senate before the vacancy arose.8Office of the Law Revision Counsel. 3 USC 19 – Vacancy in Offices of Both President and Vice President
How the Secretaries Get the Job
The Constitution gives the President the power to nominate cabinet secretaries, but every nominee must receive Senate confirmation before taking office. Article II, Section 2 requires the “Advice and Consent of the Senate” for all principal officers of the executive departments.9Congress.gov. Constitution Annotated – Article II Section 2 In practice, that means public hearings before the relevant Senate committee, where senators question the nominee on qualifications, policy positions, and potential conflicts of interest.
Confirmation requires a simple majority vote. Most cabinet nominees are confirmed relatively quickly, and many have been approved by voice vote without significant debate.10U.S. Senate. About Executive Nominations Cabinet secretaries serve at the pleasure of the President and can be removed at any time without Senate approval. As of 2026, the annual salary for all cabinet-level positions is $253,100, set by the Executive Schedule at Level I.11U.S. Office of Personnel Management. Salary Table No. 2026-EX Rates of Basic Pay for the Executive Schedule