William Freeman Vilas was born in Chelsea, Vermont, on July 9, 1840. In 1851, the Vilas family moved from Vermont to Madison, Wisconsin. After attending common schools, Vilas entered the University of Wisconsin in 1854. He then studied law at the University of Albany in New York, graduating in 1860. Although Vilas was admitted to the Wisconsin bar upon graduation, the outbreak of the Civil War led him to volunteer in the Union Army; he eventually rose to the rank of lieutenant colonel. At the end of the war, he returned to Wisconsin to practice law, and in 1868, he became a professor of law at the University of Wisconsin.

In 1884, Vilas served as the chairman of the Democratic National Convention in Chicago, which nominated Grover Cleveland for President. Only a week before Cleveland's inauguration in 1885, Vilas received word that the President had selected him for a cabinet position. Although he was unsure of which specific office he was to assume, he traveled to Washington, D.C, and took office as the thirty-third postmaster general. Once in office, Vilas faced enormous pressure to place fellow Democrats in postmaster positions since the Democrats had been out of power for almost a quarter of a century. He was criticized for his fervent partisanship in removals and appointments. When Secretary of the Interior Lucius Q.C. Lamar received an appointment to the Supreme Court in December 1887, President Cleveland nominated Vilas to become secretary of the Interior. During his short tenure, Vilas brought efficiency to the department through tightening rules, reducing the budget, and other restructuring moves. Vilas ended his tenure as secretary of the Interior in March 1889, after President Cleveland lost his bid for reelection, In 1891, the Wisconsin legislature elected Vilas to the U.S. Senate, where he served until 1897. Vilas then became a as regent of the University of Wisconsin in 1898. He died in 1908.