Howell was a representative in the territorial House of Representatives from 1886 to 1892. He served a term in the Utah State Senate from 1896 to 1900, and during the same period he was also a regent of the University of Utah. He moved to Logan in 1901 and was elected as a Republican to the United States House of Representatives in 1902. He was elected to seven consecutive terms, but he failed to secure the Republican party nomination to an eighth term in 1916.
Perhaps Howell's most significant accomplishment was his work in support of the establishment of a Bureau of Mines and the hearings that were conducted on mine disasters. He advocated high tariffs to protect western sugar, wool, and mining industries. A confirmed Republican, he stood with William Howard Taft in 1912 when Theodore Roosevelt challenged the incumbent. As a territorial representative, he was instrumental in the decision to locate the agricultural college in Logan, and later, as a congressman, he resisted a proposal to move the college from Logan to Salt Lake City. He died 18 July 1918 and was buried in the Logan City Cemetery.