Margaret Madeline Chase Smith (née Chase; December 14, 1897 – May 29, 1995) was an American politician. A member of the Republican Party, she served as a U.S. representative (1940–1949) and a U.S. senator (1949–1973) from Maine. She was the first woman to serve in both houses of the United States Congress. A Republican, she was among the first to criticize the tactics of Joseph McCarthy in her 1950 speech "Declaration of Conscience".

Smith was a candidate for the Republican presidential nomination in the 1964 election; she was the first woman to be placed in nomination for the presidency at a major party's convention. Upon leaving office, she was the longest-serving female senator in history, a distinction that was not surpassed until January 4, 2011, when Senator Barbara Mikulski from Maryland exceeded her record. Smith was ranked as the longest-serving Republican woman in the Senate, a distinction that was not surpassed until January 3, 2021, when Susan Collins, who holds the same Senate seat she previously held, was sworn in for a fifth term.

Margaret Chase was born in Skowhegan in central Maine, to Carrie Matilda (née Murray) and George Emery Chase. She was the oldest of six children, two of whom did not survive to adulthood. Her father was of English ancestry, a descendant of immigrants to the original Thirteen Colonies in the 17th century; her great-great-grandfather commanded an artillery company during the War of 1812, and her grandfather served in the Union Army during the Civil War. Her mother's family was French Canadian, having immigrated from Quebec in the middle of the 19th century; her grandfather Lambert Morin changed his name to John Murray to avoid anti-French Canadian and anti-Catholic prejudice. Her father was the town barber, and her mother worked as a waitress, store clerk, and shoe factory worker.

She received her early education at Lincoln and Garfield Elementary Schools. At age 12, she went to work at a local five-and-dime store and even bought herself a life insurance policy. She also shaved her father's customers when he was busy or away from the shop. She attended Skowhegan High School, graduating in 1916. During high school, she played on the girls' basketball team, of which she was captain in her senior year. She also worked as a substitute operator with a telephone company during this time. In that position she met Clyde Smith, a prominent local politician, who arranged a job for her as a part-time assistant to the tax assessor.

Following her high school graduation, Chase briefly taught at the Pitts School, a one-room school near Skowhegan. She also coached the girls' basketball team at Skowhegan High (1917–18). She was a business executive for the Maine Telephone and Telegraph Company (1918–1919) before joining the staff of the Independent Reporter, a Skowhegan weekly newspaper (owned by Clyde Smith) for whom she was circulation manager from 1919 to 1928. She became involved with local women's organizations. She co-founded the Skowhegan chapter of the Business and Professional Women's Club in 1922, and served as editor of the club's magazine, The Pine Cone. From 1926 to 1928, she was president of the statewide organization, the Maine Federation of Business and Professional Women's Clubs. She was a member of the Junior League of Bangor, ME. She became treasurer of the New England Waste Process Company in 1928 and was also employed as an office worker with the Daniel E. Cummings Woolen Company, a local textile mill.

On May 14, 1930, Chase married Clyde Smith, who was 21 years her senior. She soon became active in politics and was elected to the Maine Republican State Committee, on which she served from 1930 to 1936. After Clyde was elected to the U.S. House of Representatives from Maine's 2nd congressional district in 1936, Smith accompanied her husband to Washington, D.C., to serve as his secretary. In this position, she managed his office, handled his correspondence, conducted research, and helped write his speeches. She also served as treasurer of the Congressional Club, a group composed of the wives of congressmen and Cabinet members.

In the spring of 1940, Clyde Smith fell seriously ill after suffering a heart attack, and asked his wife to run for his House seat in the general election the following September. He prepared a press release in which he stated, "I know of no one else who has the full knowledge of my ideas and plans or is as well qualified as she is, to carry on these ideas and my unfinished work for my district." He died on April 8 of that year, and a special election was scheduled on the following June 3 to complete his unexpired term. Facing no Democratic challenger, Smith won the special election and became the first woman elected to Congress from Maine. Three months after the special election, she was elected to a full two-year term in the House in her own right. Smith defeated Edward J. Beauchamp, the Democratic mayor of Lewiston, by a margin of 65–35%. She was re-elected to three more terms over the course of the next eight years, never receiving less than 60% of the vote.

During her tenure in the House, Smith developed a strong interest in issues concerning the military and national security. After being appointed to the House Naval Affairs Committee in 1943, she was assigned to the investigation of destroyer production, and made a 25,000-mile (40,234-km) tour of bases in the South Pacific during the winter of 1944. She also became the first and only civilian woman to sail on a U.S. Navy ship during World War II. She became known as "Mother of the WAVES" after introducing legislation to create that organization. Although Congresswoman Smith was a strong supporter of women in the armed services, she did not write the legislation that created the special female military units during World War II. She did, however, champion the legislation that gave women permanent status in the military following the war.