On this date in 1901, William McKinley appointed 47-year-old Philander C. Knox as the 45th Attorney General. He stayed on in that post under Theodore Roosevelt, and resigned on June 30, 1904, to take his seat in the Senate representing Pennsylvania. He left the Senate in March 1909, when William Howard Taft appointed him the 40th Secretary of State. Following the end of Taft's term, Knox went back to practicing law. In 1916, he was again elected to the Senate, and died in office in 1921.
Knox is one of 13 Cabinet Secretaries to serve under three or more Presidents.