Joseph C. O'Mahoney, a native of Massachusetts, Attended Columbia University in New York. He moved to Boulder, Colorado, in 1908 and was a reporter on the Boulder Herald until he came to Cheyenne in 1916 where he served as city editor of the Cheyenne Leader. He was executive secretary to Senator John B. Kendrick in Washington, D.C., 1917-1920, when he was graduated from the Georgetown University Law School. Admitted to the Wyoming Bar in 1920, he began practice in Cheyenne and Washington. He was a delegate to the Democratic state conventions from 1924-1932 and to the Democratic national conventions 1924-1948. He was appointed first assistant Postmaster General on March 6, 1933, and he served until December when he was appointed to fill a vacancy in the Senate. He was elected in 1934, reelected in 1940, an again in 1946. He was in the Senate from January 1, 1934 to January 3. 1953. He was unsuccessful in the general election in November 1952, but was elected again November 2, 1954, this time to fill the vacancy caused by the death of Senator Lester C. Hunt. He was also elected for the full term commencing January 3, 1955, and he served until January 3, 1961. He was not a candidate for renomination in 1960, when he resumed the practice of law in Washington. He died December 2, 1962.