Broomfield was a member of the Michigan State House of Representatives, 1949–1954, serving as speaker pro tempore in 1953. He served in the Michigan State Senate in 1955 and 1956. In 1956, Broomfield was elected as a Republican from Michigan's 18th District to the United States House of Representatives for the 85th and to the seventeen succeeding Congresses, serving from January 3, 1957 to January 3, 1993. Due to redistricting following U.S. Censuses, Broomfield served the 19th District, 1973–1983 and the 18th District, 1983–1993. He was not a candidate for renomination in 1992 to the 103rd Congress. The 18th District was discontinued following the 1990 census and for the most part redistricted as the 11th which elected Joe Knollenberg in 1993. During his tenure in Congress, Broomfield served as a member of the U.S. House Committee on Foreign Affairs and was ranking member from 1975 until his retirement in 1993. At the time of his retirement, he was the longest serving Republican then serving in the House of Representatives. During his years of service in the House, Broomfield garnered praise from both sides of the aisle for his ethics, honesty and statesmanship. When he retired, he left behind a legacy of bipartisan friendship and cooperation. Broomfield voted in favor of the Civil Rights Acts of 1957, 1960, 1964, and 1968, as well as the 24th Amendment to the U.S. Constitution and the Voting Rights Act of 1965.
Retirement
After retirement, Broomfield started a foundation in Michigan that supports various charities in southeast Michigan, including the efforts to cure cancer, spina bifida, Alzheimer's, and the Salvation Army. A longtime resident of Lake Orion, Michigan, he last lived in Kensington, Maryland. In September 2000, Congress designated the Royal Oak Post Office at 200 West 2nd Street in Royal Oak, Michigan as the William S. Broomfield Post Office Building. On December 30, 2006, Broomfield collapsed at the state funeral memorial for former U.S. President Gerald Ford at the United States Capitol, bringing the ceremonies to a temporary pause. The reason given for the collapse was exhaustion. Broomfield's wife Jane died on March 21, 2013 at the age of 97, due to heart failure. Broomfield died on February 20, 2019 at the age of 96 in Kensington, Maryland, where he resided in his later years.
