At the time of the 1831 census, the borough included just over 1,000 houses and had a population of 4,536. The Reform Act expanded the boundaries to bring in the neighbouring parishes of Eaglesfield, Brigham, Papcastle and Bridekirk, and part of Dovenby, increasing the population to 6,022 and encompassing 1,325 houses. This made the borough big enough to retain both its members. However, in the next wave of reform, introduced at the 1868 general election, one of Cockermouth's two seats was withdrawn, and in 1885 the borough was abolished altogether, although the name was transferred to the surrounding county constituency.