Between 1870 and 1920 civic inventiveness reached a crescendo unmatched in American history, not merely in terms of numbers of clubs, but in the range and durability of the newly founded organizations. Social historian Theda Skocpol and her colleagues have shown that half of all the largest mass membership organizations in American history—the fifty-eight national voluntary organizations that ever enrolled at least 1 percent of the adult male or female population—were founded in the decades between 1870 and 1920.11
