Frank Denholm was a member of the United States House of Representatives from South Dakota from 1971-1975. He worked as a farmer and auctioneer, and engaged in the business of interstate trucking. He was elected to the position of Day County sheriff in 1950, and served in that capacity through 1952, and later joined the Federal Bureau of Investigation in 1956, serving there through 1961. He was admitted to the bar in 1962 and started his legal practice in Brookings, South Dakota. During this time, he also served as a lecturer in economics, law, and political science at South Dakota State University. He was a delegate to the South Dakota State Democratic conventions in 1950 and 1952, and later to the Democratic National Convention in 1968. He was elected as a Democrat to the United States House of Representatives in 1971, and remained in that role until 1975, after losing the election in 1974. He then returned to the practice of law in Brookings, South Dakota, the city in which he lived after office.