Beginning in the 1850s Canadians had access to closer and cheaper sources of roofing slate than those historically provided by European and British roofer quarries. Slate quarrying had taken place in the northeastern United States since 1734 but only started to be exploited on a large scale in the 1850s. Railway and urban development in Canada encouraged the export of United States roofing slate north, a pattern of trade that was further supported by the Reciprocity Treaty of 1854 which exempted American slate from duty. Tables of the Trade and Navigation of the Province of Canada for the period of the treaty from 1854 to 1866 show that, except for three years when a small portion was admitted from Great Britain, all the slate imported into Canada came from the United States. The value of the American slate imported under the Reciprocity Treaty reached a high point of $12,763 in 1859, its subsequent decline reflecting the disruptive effect of the Civil War on American production and the development of domestic sources in the 1860s.
The Geological Survey of Canada identified localities in the Eastern Town ships of Quebec suitable for quarrying roofing slate as early as 1847. Specimens of roofing slate from Kingsey, Frampton, Melbourne, Shipton and Tring were shown at world industrial exhibitions in London (1851) and Paris (1855). Quarries operated briefly at Shipton and Kingsey in the 1850s but the first viable enterprise was the Walton Slate Quarry established in the township of Melbourne in 1861.