The IBT was officially formed in 1903 in Niagara Falls, New York, as the merger of several different groups representing teamsters. The group expanded to include truck-drivers in the 1920s, and grew during the hard times of the Great Depression and World War II. By 1949, its membership had topped one million.
At the 1957 IBT convention held in Miami Beach, Florida, Jimmy Hoffa was elected president of the union, which then had 1.5 million members. In the next two decades, Hoffa's legal troubles and union ties to organized crime signaled a long period of descent. Like most American unions, the IBT has seen a decline in membership over the past 20 years.