Born in Kingston, Missouri, Hughes attended the common schools and graduated from Richmond College in 1871. He then graduated from the law department of the University of Missouri in Columbia in 1873, was admitted to the bar in 1877, and commenced practice at Richmond, Missouri. He moved to Denver, Colorado in 1879.
Hughes was a presidential elector on the Democratic ticket in 1900. He was professor of mining law in the law school of the University of Denver and Harvard University. He was elected as a Democrat to the United States Senate and served from March 4 1909, until his death in Denver. He was interred in Fairmont Cemetery.