William attended elementary and high schools in Porterville,[1] also assisting his father in his trade; Martha Traeger died in 1895.

He compiled a 3–1–1 record while coaching at USC; the schedule was entirely against southern California teams, including games against Pomona and Occidental as well as Los Angeles High School, a team he had coached in 1906, and a San Bernardino County athletic club, the only contest outside L.A. County.

In 1921, Traeger was appointed Sheriff of Los Angeles County; he was elected to 4-year terms in 1922, 1926 and 1930, serving until December 1932.

In 1932, Traeger was elected as a Republican to the 73rd United States Congress (March 4, 1933 – January 3, 1935)[1] despite the Democratic landslide which occurred that year.

Traeger died at age 54 of a liver disorder at the Wadsworth Hospital in Los Angeles, two weeks after leaving office; he had become ill in late December.