South Hadley, residential town (1990 pop. 16,685), Hampshire co., W Mass., on the Connecticut River near the Holyoke Range; settled 1684, inc. 1775. Its paper industry dates from the early 19th cent. Electronic equipment, machinery, metal stampings, and concrete products are also made, although the area has suffered from a decline in manufacturing. The first navigable canal in the United States began operation there in 1795. Mount Holyoke College is in South Hadley.