He was elected as a Republican to the Vermont House of Representatives in 1938 and served two terms. He was elected Speaker of the House in his second term, serving from 1941 to 1943. He was elected to the Vermont Senate in 1942, served from 1943 to 1945, and was elected President Pro Tempore. He was elected Lieutenant Governor of Vermont in 1944 and 1946, serving from 1945 to 1949. Throughout much of Vermont history Governors and Lieutenant Governors had served two one-year terms, and later one two-year term as part of the Republican Party's "Mountain Rule." However, Ernest W. Gibson, Jr. had successfully challenged the established structure to win the governorship in 1946. Gibson defeated Emerson in the 1948 Republican primary and went on to win reelection to a second term. Emerson's fellow conservative Harold J. Arthur succeeded Emerson as Lieutenant Governor. When Arthur unexpectedly became governor in 1950 after Gibson resigned to accept a federal judgeship, Arthur served out Gibson's term but declined to run for a full term himself, clearing the way for Emerson's comeback. Emerson was elected Governor in 1950 and reelected in 1952, serving from 1951 to 1955. As Governor, he recommended that Vermont citizens serving in the Korean War be paid a bonus by the state. He supported studies of the feasibility of building a natural gas pipeline for Vermont and of possible racial discrimination in the state. Also during his administration, legislation known as the Forest Act was passed, providing assistance for municipalities to establish forests. Emerson also played a role in "The Novikoff Affair," in which a tenured University of Vermontprofessor Alex B. Novikoff was dismissed for alleged Communist sympathies that were never substantiated.
Post gubernatorial career
In 1958, he ran unsuccessfully for the United States Senate, losing the Republican nomination to Winston Prouty. In 1960 Emerson was an unsuccessful candidate for the Republican nomination for Vermont's lone seat in the United States House of Representatives, losing to incumbent Governor Robert T. Stafford. Stafford went on to victory in the general election, defeating one term incumbent William H. Meyer, the first Democrat elected statewide in more than 100 years.
Personal
Emerson married Dorcas M. Ball on August 4, 1927. They had two children, Nancy and Cynthia.
Death and burial
He died in Berlin, Vermont, on May 26, 1976. He is buried at Welcome O. Brown Cemetery in Barton.