The secretary of state can conduct negotiations, interpret, and terminate treaties relating to foreign policy.

The secretary also can participate in international conferences, organizations, and agencies as a representative of the United States.

Most of the historical domestic functions of the Department of State were gradually transferred to other agencies by the late 19th century as part of various administrative reforms and restructurings.

[15] Those that remain include storage and use of the Great Seal, performance of protocol functions for the White House, and the drafting of certain proclamations.

Six past secretaries of state – Jefferson, Madison, Monroe, John Quincy Adams, Van Buren and Buchanan – have gone on to be elected president.

Others, including Henry Clay, Daniel Webster, Lewis Cass, John C. Calhoun, John M. Clayton, William L. Marcy, William Seward, Edward Everett, Jeremiah S. Black, James Blaine, Elihu B. Washburne, Thomas F. Bayard, John Sherman, Walter Q. Gresham, William Jennings Bryan, Philander C. Knox, Charles Evans Hughes, Elihu Root, Cordell Hull, Edmund Muskie, Alexander Haig, John Kerry, Hillary Clinton, and Marco Rubio have also campaigned as presidential candidates, either before or after their term of office as secretary of state, but were ultimately unsuccessful.

The following timeline depicts the progression of the secretaries of state and their political affiliation at the time of assuming office.