By the middle of the 18th century the woollen trade was well-established in Oldham. In the 1790s, mechanized spinning and weaving caused cotton to supplant wool as the main industry. Oldham was a popular place to build cotton mills. Standing on the western slopes of the Pennines, where the damp atmosphere prevented the fibre from drying out and snapping when being spun and woven, six cotton mills had been built in the town by 1778. A branch of the Ashton Canal was completed in 1796 and this helped the local collieries to provide cheap fuel for the steam-powered textile machines.


Industrial workers in Oldham played a prominent role in the struggle for the vote. After hearing Major John Cartwright, explain his views on parliamentary reform in 1816, Joseph Healey formed a Hampden Club in the town. Oldham also had a flourishing Female Political Union, and John Tyas of the Times, claimed that 150 women from the organisation attended the meeting in Manchester on 16th August, 1819, that resulting in the Peterloo Massacre. After the passing of the 1832 Reform Act, Oldham elected the two Radical candidates, John FieldenWilliam Cobbett.

By 1838 Oldham had over 213 cotton factories. This was even more than other leading cotton towns such as Manchester (182), Rochdale (117) and Bury (114). The railways also helped the growth of the town. In 1839 a railway between ManchesterLeeds began operating. Three years later the Oldham branch of the Lancashire & Yorkshire Railway was completed. By 1861 the population of the town had reached 72,000. and and