Born in Brighton, Washington County, Iowa, Cushman attended the public schools in Brighton and Pleasant Plain Academy in Pleasant Plain, Iowa. He moved to Albany County, Wyoming, in 1885. He was employed as a ranch hand and as a teacher. He studied law. He was admitted to the bar in 1889 and commenced practice in Bassett, Nebraska. He moved to Tacoma, Washington, in 1891 and continued the practice of law. He served as member of Troop B, First Cavalry, Washington National Guard from 1896 to 1903.
Cushman was elected as a Republican to the Fifty-sixth and to the five succeeding Congresses and served from March 4, 1899, until his death in New York City July 6, 1909. The remains were cremated and the ashes interred in Tacoma Cemetery, Tacoma, Washington.
This article incorporates public domain material from the Biographical Directory of the United States Congress website http://bioguide.congress.gov.