in the 1920s, the durham-middlefield route continuing towards meriden was designated as a secondary state highway known as highway 330. it ran more or less along the alignment of modern route 147. in the 1932 state highway renumbering, old highway 330 was renumbered to route 147. at the same time, the middlefield-middletown route was created as route 157. by 1938, route 157 took over the durham road portion of route 147. in 1966, however, this change was reversed and route 157 was extended to the southwest towards along its modern alignment south of route 147.