Following the retirement of two-term State Senator Roy V. Wright in 1947, Clapp became a candidate for the State Senate. He was re-elected to a second term in 1951.
In 1953, with Governor Alfred Driscoll term-limited, Clapp sought the Republican nomination for Governor of New Jersey in 1953. He secured the organization lines in Essex and Bergen counties, but dropped out of the race on February 28, 1953.
Superior Court Judge
Clapp resigned from the Senate in 1953 after Governor Driscoll nominated him to serve as a Superior Court Judge. He was the Presiding Judge of the Appellate Division. He resigned from the bench in 1957.
Candidate for State Senator
In 1959, Clapp again sought election to the State Senate. Essex County Republicans were divided into two factions; Clapp led a slate of reform candidates opposed to the Essex County Republican Chairman, William Yeomans. Clapp defeated Essex County Prosecutor Charles V. Webb, Jr. in the Republican primary, 31,551 to 12,177. Clapp's "Clean Government" slate of 12 Assembly candidates all won the primary against the organization ticket. His landslide victory in the 1959 primary paved the way for former Congressman Robert W. Kean to oust Yeomans in a race for Essex County Republican Chairman one week later. Among the political newcomers who ran on the Clapp ticket was C. Robert Sarcone. Unable to unify the Republican Party after the primary, Clapp was unable to unseat Democratic incumbent Donal C. Fox. He lost by 14,582 votes, 126,800 to 112,218.
Legal Scholar
Clapp was the Dean of the Rutgers University School of Law from 1951 to 1953, and also served as Essex County Bar Association president. He was the author of a seven-volume work, Wills and Administration in New Jersey, and the chairman of the New Jersey Supreme Court Civil Practice Committee from 1947 to 1987. On and off between 1929 and 1971, Clapp was a Law Professor at the Mercer Beasley School of Law and the Rutgers Law School. He was Chairman of the New Jersey Institute for Continuing Legal Education from 1962 to 1986.
Later Years
Clapp founded a law firm, Clapp & Eisenberg, in Newark, New Jersey. In 1977, he served as Chairman of Thomas Kean's campaign for the Republican gubernatorial nomination. He was married to Catharine Shotwell Clapp. They had four sons and seven grandchildren. Clapp died in 1988 at age 84.
