Route 75 in the U.S. states of Connecticut and Massachusetts is a 17.5-mile-long (28.2 km) scenic route connecting the Hartford, Connecticut, and Springfield, Massachusetts, areas. The route begins at Route 159 in the town of Windsor, Connecticut, and ends at the junction of Route 159/Route 147 in the city of Agawam, Massachusetts.

Route 159 is a 21.14-mile-long (34.02 km) state highway connecting the Hartford and Springfield areas in the U.S. states of Connecticut and Massachusetts. It begins as the northern extension of Main Street in Hartford and proceeds northward along the west bank of the Connecticut River towards Agawam, Massachusetts. The route ends at the junction of Route 147 and Route 75 in Agawam center just south of the West Springfield city line. The route was originally designated as U.S. Route 5A in 1932 and was renumbered to its modern designation in October 1968.