The history of rail transport in Canada began in the early 19th century. The Canadian railway system saw several expansion "booms" throughout history, as well as a major change from broad to standard gauge which occurred in the 1870s. An initially disconnected system was gradually integrated with the American railway network, as Canadian and American railway companies built lines and bought smaller companies in each other's country. The Intercolonial Railway, a product of Canadian Confederation, was Canada's first major experiment in railway nationalization, and following Confederation, several transcontinental railways were built.