In 1923 Runyon was appointed Judge of the United States District Court for the District of New Jersey, and he remained on the bench until his death.
Runyon, a Republican, served on Plainfield Common Council from 1897 to 1898 and was the Judge of Plainfield's City Court from 1899 to 1910.
Runyon was a member of the New Jersey General Assembly from 1915 to 1917, and served in the New Jersey Senate from 1918 to 1922.
He was serving as President of the Senate when Walter Evans Edge resigned the governorship in order to accept the United States Senate seat to which he had been elected in 1918. At the time New Jersey had no Lieutenant Governor, so Runyon succeeded to the governorship. He served from May 16, 1919 to January 13, 1920. Runyon was defeated in the 1919 Republican primary for Governor.
US District Courts Judge, Judges, Class of 1894, Runyon, District of New Jersey, New Jersey, District Court