The United States Secretary of State is the head of the United States Department of State, concerned with foreign affairs. The Secretary is a member of the Cabinet and the highest-ranking cabinet secretary both in line of succession and order of precedence. The current Secretary of State is Hillary Rodham Clinton, the 67th person, and third woman to hold the post. The specific duties of the Secretary of State include:

The original duties of the Secretary of State include some domestic duties, such as:

Most of the domestic functions of the Department of State have been transferred to other agencies. Those that remain include storage and use of the Great Seal of the United States, performance of protocol functions for the White House, and the drafting of certain proclamations. The Secretary also negotiates with the individual States over the extradition of fugitives to foreign countries. President Nixon's resignation, a domestic issue, was also addressed to the Secretary of State.

As the highest-ranking member of the cabinet, the Secretary of State is the third-highest official of the executive branch of the Federal Government of the United States, after the President and Vice President and is fourth in line to succeed the Presidency, coming after the Vice President, the Speaker of the House of Representatives, and the President pro tempore of the Senate. Six Secretaries of State have gone on to be elected President.