The introduction of textile manufacture during the Industrial Revolution initiated a process of rapid and unplanned urbanisation. A building boom began in Crompton during the mid-19th century, when suitable land for factories in Oldham was becoming scarce. By the late 19th century Crompton had emerged as a densely populated mill town. Forty-eight cotton mills—some of the largest in the United Kingdom—have been recorded as existing in the area. At its spinning zenith, as a result of an interwar economic boom associated with the textile industry, Shaw and Crompton was reported to have had more millionaires per capita than any other town in the world. Imports of foreign cotton goods began the decline in the region's textile industry during the mid-20th century; Shaw and Crompton's last mill closed in 1989.