town and borough (district), administrative and historic county of Lancashire, England. It lies on the northwest periphery of the Greater Manchester metropolitan area. The west of the borough is part of the rich agricultural Lancashire Plain, and in the east the land rises to the Pennine moorlands. The town grew duing the Industrial Revolution as a centre of cotton weaving and calico printing. Textile mills continue to operate in Chorley, and machinery for the mills has been manufactured locally since 1866. Other industries include motor engineering (British Leyland), paint manufacturing, and rubber. Astley Hall, an Elizabethan mansion set in parkland, was presented to the borough as a World War I memorial. The borough encompasses a largely rural area surrounding the town of Chorley. Area 79 square miles (204 square km). Pop. (2001) town, 33,424; borough, 100,449.