Clarence Emir Allen was born 8 September 1852 in Girard Township, Erie County, Pennsylvania. He spent his childhood in Ohio, where he graduated from Grand River Institute at Austinburg in 1872, and from Western Reserve College at Hudson in 1877. After his graduation from Western Reserve, he returned to teach at Grand River Institute and to marry on 28 November 1877 Corinne M. Tuckerman, whose father was principal of the Institute. They were the parents of six children.
In 1878 Allen accepted a position as principal of Western Reserve College Preparatory School. After three years there he moved to Salt Lake City in August 1881, where he was an instructor in the Salt Lake Academy until 1886. That year he resigned to take a position with the Old Jordan and South Galena Mining Companies.
In 1888 Allen was elected to the Utah Territorial House of Representatives and was subsequently reelected in 1890 and 1894. In the territorial legislature he worked to secure passage of public education bills to provide free public education to Utah's children between six and eighteen years of age. He also worked for passage of a free library bill, which passed the territorial legislature, but was vetoed by Governor Caleb West. In August 1890 he was elected Salt Lake County Clerk and held that position through 1892. As a Republican in favor of unlimited coinage of silver, he walked out of the 1896 Republican convention along with other western delegates in protest of the party's adoption of a plank favoring the gold standard.
After studying law, he was admitted to the Utah bar in 1893 and opened a legal practice in Salt Lake City. Clarence Allen served from January 1896 until March 1897 as one of Utah's first two representatives to the United States House of Representatives. Allen served only one year in the U.S. House of Representatives, declining to be renominated for the office in 1896. After his return to Salt Lake City, he took a position as general manager of the Centennial-Eureka Mining Company. He retired in 1922 and moved to Columbus, Ohio. He died on 9 July 1932 in Escondido, California. His remains were cremated and the ashes interred in Mount Olivet Cemetery in Salt Lake City.
Allan Kent Powell