What we now call distance education began long before computers linked students and teachers. Beginning in the late nineteenth century, hundreds of private companies, public universities, and enterprising individuals sold instruction by mail. Nearly any subject could be pursued, but vocational training was the best seller. The company that dominated the field, enrolling nearly 100,000 new students annually in the early twentieth century, was in Scranton, Pennsylvania, where its massive headquarters was known as the Big Red Schoolhouse. By comparison, the largest proprietary school in Philadelphia, Peirce College, never enrolled more than 2,000 students until World War I.