Muriel Fay Humphrey Brown (née Buck; February 20, 1912 – September 20, 1998) was an American politician who served as the second lady of the United States from 1965 to 1969, and as a U.S.

She attended Huron College and met her future husband; Hubert Humphrey in 1934, when she was twenty-two years old and working as a bookkeeper.

Hubert Humphrey ran for his party's nomination in the Presidential primaries of 1960, losing to John F. Kennedy; during this campaign, Muriel made speeches for him in Wisconsin.

[6] She served as a member of the President's Committee for People with Intellectual Disabilities from 1966 to 1969,[7] convened many meetings of women associated with the Democratic Party, and travelled extensively.

Muriel was nominated by the Democratic-Farmer-Labor Party and subsequently appointed to the Senate vacancy by Minnesota Governor Rudy Perpich, serving from January 25, 1978, to November 7, 1978, in the 95th Congress.

She was the first spouse of a former vice president to serve in Congress as well as the first woman to represent Minnesota in the U.S. Senate, preceding the Democrats Amy Klobuchar and Tina Smith.

[11] According to an official Congressional biographical summary, "Muriel Humphrey pursued her own interests during her brief tenure, supporting an extension of the Equal Rights Amendment (ERA) ratification deadline and advocating several programs to benefit persons with mental disabilities.

"[12] Among the issues which she championed was public visibility for Down Syndrome, a topic she had become passionate about due to her granddaughter Victoria Solmonson's condition.

[13][14] During her husband's presidential campaign in 1967 and 1968, she visited facilities for people with Down Syndrome in Long Island and was featured by the New York Times.

[17] After consulting with President Jimmy Carter, Muriel chose not to stand as a candidate for the 1978 United States Senate special election in Minnesota for the remaining term.