The Fort Worth Stockyards functioned as one of the nation's major livestock markets and meatpacking centers from the late nineteenth century through much of the twentieth. Built up after railroads reached Fort Worth in 1876, the district's stockyards were formally organized in 1887 and expanded through the 1890s under Boston investor Greenleaf Simpson, whose Fort Worth Stockyards Company drew the major national meatpacking firms Armour and Swift to build competing plants there around 1902. The Livestock Exchange Building, known as the Wall Street of the West, housed commission companies, bankers, and buyers who handled the trading of cattle, hogs, sheep, and, during World War I, one of the world's largest horse and mule markets. Rail access let the district function as a shipping and processing hub serving ranchers across Texas and the Southwest, with operations peaking during World War II when the yards processed several million head of livestock in a single year. The rise of trucking after World War II undercut the rail-based stockyard system, and the Armour and Swift plants closed in 1962 and 1971 respectively, ending the district's role as a working meatpacking center. Today the Fort Worth Stockyards Historic District functions as a preserved entertainment and tourism district rather than a livestock-processing hub, featuring restored brick streets and buildings, western-wear and specialty shops, restaurants, rodeo venues, the Stockyards Museum, and the well-known twice-daily cattle drive that echoes the district's ranching origins.