The Canadian National Railway (CN) is a Canadian Class I freight railway headquartered in Montreal, which serves Canada and the Midwestern and Southern United States. It is Canada's largest railway, in terms of both revenue and the physical size of its rail network, spanning the country from the Atlantic coast in Nova Scotia to the Pacific coast in British Columbia across approximately 20,000 route miles (32,000 kilometres) of track. In the late 20th century, CN gained extensive capacity in the United States by taking over railroads such as the Illinois Central and others. This photograph shows a CN EMD SD70M-2, SD75I and SD60F unit in the Canadian Rockies north of Jasper, Alberta.Photograph credit: David Gubler