Willimantic became a city when its charter was revised in 1893. Up to the outbreak of World War II, it continued to be a center for the production of silk and cotton thread. Various groups of immigrants arrived over the years to work in the mills. The city was a major rail hub; in the early twentieth century, as many as a hundred trains ran through Willimantic daily. Ornate Victorian homes were built in the town's Prospect Hill section, and the town prospered, growing from a population of less than 5,000 in 1860 to more than 12,100 by 1910.