The Canadian petroleum industry arose in parallel with that of the US. The first oil well in North America was dug in Ontario in 1848 by using picks and shovels, one year before the first oil well in the United States had been drilled in Pennsylvania. By 1870, Canada had 100 oil refineries in operation and was exporting oil to Europe. However, the oil fields of Ontario were shallow and small, and oil production started to decline around 1900 while as the automobile started to become popular. In contrast, US oil production grew rapidly after huge discoveries had been made in Texas, Oklahoma, California, and elsewhere. By the end of World War II, Canada imported 90% of its oil, mostly from the US.