After graduating from Columbia, Newton was the Director of Historical Research for Webster Publishing Company in St. Louis, Missouri. His first post in a long career in cultural heritage was as the director of the Vermont Historical Society in Barre, Vermont, where he worked from 1942–1950. During this time, he helped found two magazines, American Heritage and Vermont Life. From 1944–1946, he took a two-year hiatus from Vermont during World War II to serve in the U.S. Navy as a lieutenant at Pearl Harbor. Newton served as director of Old Sturbridge Village in Sturbridge, Massachusetts from 1950–1954, and then spent two years pursuing academic research; first as the director of the Institute on Historical and Archival Management at Harvard University and Radcliffe College, and then as a Fulbright fellow in England. He was a senior research scholar at the University of London as well as a lecturer at Uppsala University in Sweden. When Newton returned to the United States in 1956 he became the director of Pennsylvania's Bureau of Museums and Historic Sites and Properties. During this time he also served as director of the Museum of Art, Science, and Industry in Bridgeport, Connecticut. In 1959, Newton was hired to serve as the executive director of the newly established St. Augustine Historical Restoration and Preservation Commission, whose goal was to restore and reconstruct historic buildings in downtown St. Augustine, Florida. They hoped these buildings would become part of a Spanish colonialmuseum village in similar fashion to Colonial Williamsburg or Old Sturbridge Village. He also became the director-general of the National Quadricentennial Commission, a committee appointed by President John F. Kennedy to plan St. Augustine's 400th anniversary celebration. In 1962, he became the president of St. Augustine Restoration, Inc., a foundation created by the St. Augustine Historical Restoration and Preservation Commission to raise private funds for restoration work inthe city. Newton resigned as director of the Commission in 1968 and became the director of the Pensacola Historical Restoration and Preservation Commission. He founded the Museum of the Americas in Brookfield, Vermont and was a professor in art at Norwich College in Northfield, Vermont. This museum, which was housed in an old church, was visited by art dealerPhilip Mould and found to contain over three hundred works by artists such as William Hogarth and Joseph Wright of Derby, as well as American painters such as Gilbert Stuart and Robert Feke. When Mould made his visit, however, the paintings were found to be "mostly in various stages decay, with layers of mildew covering their surfaces" and Mould described it as "not a museum collection, it was a hidden hoard." He later returned to St. Augustine to once again serve as director of the Commission, since renamed the Historic St. Augustine Preservation Board. The Preservation Board was abolished by the State of Florida in 1997 in accordance with the Sundown Act.
