 During the mid-20th century, both Hartford and Springfield experienced a loss of manufacturing during economic restructuring.The growth of the highway system—in particular Interstate 91—engendered white flight to the suburbs, where a disproportionate amount of both cities' wealthy citizens live, (e.g., in Longmeadow, Massachusetts and West Hartford, Connecticut).During the 1960s and 1970s, the Connecticut River was polluted and Interstate 91 was built along both riverfronts – slicing through existing neighborhoods.