Lancashire emerged as a major commercial and industrial region during the Industrial Revolution. Manchester and Liverpool grew into its largest cities, dominating global trade and the birth of modern capitalism. The county contained several mill towns and the collieries of the Lancashire Coalfield. By the 1830s, approximately 85% of all cotton manufactured worldwide was processed in Lancashire. Accrington, Blackburn, Bolton, Burnley, Bury, Chorley, Colne, Darwen, Nelson, Oldham, Preston, Rochdale and Wigan were major cotton mill towns during this time. Blackpool was a centre for tourism for the inhabitants of Lancashire's mill towns, particularly during wakes week.