For the first decade and a half of his career, Haynes primarily designed his buildings in the Colonial Revival style.
He designed a number of major buildings in this style, including the Community Memorial Hospital and the Randall Hotel.
In this style, he designed the Anthony Building on the Fitchburg State campus, the high school at Uxbridge, and the Latchis Hotel in Brattleboro, Vermont.
After the beginning of the war he gradually transitioned to the International Style, thus embracing modernism.
Large educational complexes of this era include the high schools at Saugus, East Longmeadow, Lincoln-Sudbury Regional, and North Andover.