In the 1920s, State Highway 112 followed today's Route 77, and part of Route 17, from Guilford through Durham to Middletown.

The modern Route 112, commissioned in 1932, has not changed much since the 1930s. Its official length has decreased 0.07 mile since then, which could be a smoother curve or two, or simply a corrected measurement. It follows a route over which iron ore was once transported in saddle-bags from the numerous Salisbury workings to Lime Rock forges.

Route 41 intersection relocated, early 1930s

Between 1932 (old alignment shown on map) and 1934 (aerial photo) Routes 41 and 112 were realigned in Salisbury. They used to meet at a T-intersection at where the main building of the Hotchkiss Prep School stands now. A short overlap of 41/112 then continued east and south to roughly where the two roads meet now at a 4-way intersection. North Road (straighter at the time) was part of former Route 41. A grass path between a row of trees marks the old part of Route 112. When the two roads were improved and realigned, Hotchkiss consolidated or expanded its campus.