Margaret Chase Smith (December 14, 1897 - May 29, 1995) was a Republican Senator from Maine, and one of the most successful politicians in Maine history. She was the first woman to be elected to both the U.S. House and the Senate. She was the first woman to have her name placed in nomination at her party's convention (1964 Republican).

She first won a seat to the House of Representatives on June 3, 1940 to fill the vacancy caused by the death of her husband, Clyde Smith . She served in the House until January 3, 1949. She had been elected to the U.S. Senate in 1948. She served in the Senate from 1949 to January 3, 1973. She was defeated for reelection in 1972 by Democrat Bill Hathaway, the only election she ever lost in the state of Maine. (Hathaway only served one term in the Senate; he was defeated in 1978 by Republican Bill Cohen).

She received the Presidential Medal of Freedom from President Bush in 1989.

Senator Smith is historically prominent not only for her many firsts as a woman, but also for her early principled opposition to the tactics of Senator Joseph McCarthy. On June 1, 1950, she gave her Declaration of Conscience on the floor of the Senate, earning McCarthy's permanent ire and the nickname "Moscow Maggie" from his staff. Her speech, although it did not produce immediate backlash, was the beginning of the end for McCarthy. She was the first (and as yet only) woman chair of the Senate Republican Conference, 1967-1972.

Preceded by: Wallace H. White, Jr.

U.S. Senators from Maine

Succeeded by: Bill Hathaway