Maryland became the seventh state to join the Union on April 28, 1788. Maryland’s first two senators, Charles Carroll and John Henry, took office on March 4, 1789. Maryland’s longest-serving senators include Millard Tydings (1927-1951), Paul Sarbanes (1977-2007), and Barbara Mikulski (1987-present). On January 3, 2011, Barbara Mikulski became the longest-serving female senator to date. Among those who rose to leadership positions are John Howard and Samuel Smith, both of whom served as the Senate’s president pro tempore. As vice president, Spiro Agnew was the Senate’s constitutional president or presiding officer.