Simpson was born in Jackson, Teton County, Wyoming, the son of Margaret and William Lee Simpson. He attended the public schools in, among other places, Meeteetse, and Cody. In 1921, he graduated from the University of Wyoming at Laramie in Albany County. While a student at UW, he was both an athlete and a member of the university's debate team. During World War I, Simpson served as a second lieutenant in the infantry, United States Army. From 1921 to 1925, he attended Harvard Law School. He was admitted to the bar in 1926 and practiced law in Cody until 1955 when he became governor of Wyoming. Simpson served as a member of the Wyoming House of Representatives from 1926 to 1927. He was a member of the board of trustees of the University of Wyoming in 1939 and president of the board from 1943 to 1954. He was a member of the National Association of Governing Boards of State Universities and Allied Institutions and served as president of the body from 1952 to 1953. Milward Simpson ran for the U.S. Senate against Joseph C. O'Mahoney in 1940, but was defeated 58.7% to 41.3%. Simpson was narrowly elected governor in November 1954. He defeated the Democrat William Jack, 56,275 to 55,163. Simpson was unseated after a single term in 1958, a heavily Democratic year nationally, after a single term in office by John J. Hickey of Rawlins in Carbon County, 55,070 to 52,488. He resumed his law practice in 1959. Simpson won a special election on November 6, 1962, to the United States Senate to fill the vacancy caused by the death of Republican Senator-elect Edwin Keith Thomson in the term ending January 3, 1967; he was not a candidate for Senate reelection in 1966 but was succeeded by outgoing Governor Clifford Hansen of Jackson. Simpson lived in Cody until his death in 1993 at the age of 95. Along with Barry Goldwater of Arizona, Norris Cotton of New Hampshire, Bourke B. Hickenlooper of Iowa, Edwin Mechem of New Mexico, and John Tower of Texas, Simpson was one of six Republican senators who voted against the Civil Rights Act of 1964. However, as governor he had signed into law Wyoming civil rights measure in 1957 which had abolished racial segregation in his state. Simpson voted in favor of the Voting Rights Act of 1965. Simpson and his wife, the former Lorna Kooi, had two sons, both of whom have the middle name "Kooi". The younger son, Alan K. Simpson, served in the Wyoming House from Park County from 1965 to 1977 and in the United States Senate as a Republican from 1979 to 1997. Alan Simpson was the Senate Republican Whip during the early 1990s. An older son, Peter K. Simpson, is a retired historian and administrator at the University of Wyoming, who served in the state House from 1981 to 1984 from Sheridan County, where he was then residing while serving as an administrator at Sheridan College. Milward Simpson's grandson, Colin M. Simpson, is a former member of the Wyoming House from Cody, who lost a Republican primary for governor in 2010 to Matt Mead of Jackson, a grandson of Clifford Hansen. As a young man, Milward Simpson played professional baseball in Cody. One of his teammates was the subsequent Lieutenant Governor and Education Superintendent Bill Dodd of Louisiana. They became close friends.
