The County Borough of Leeds, and its predecessor, the Municipal Borough of Leeds, was a local government district in the West Riding of Yorkshire, England, from 1835 to 1974. Its origin was the ancient borough of Leeds, which was reformed by the Municipal Corporations Act 1835. In 1889, when West Riding County Council was formed, Leeds became a county borough outside the administrative county of the West Riding; and in 1893 the borough gained city status. The borough was extended a number of times, expanding from 21,593 acres (8,738 ha) in 1911 to 40,612 acres (16,435 ha) in 1961; adding in stages the former area of Roundhay, Seacroft, Shadwell and Middleton parishes and gaining other parts of adjacent districts. In 1971 Leeds was the fifth largest county borough by population in England.