Chinatowns in Canada generally exist in the large cities of Vancouver, Ottawa, Calgary, Edmonton, Toronto, and Montreal, and existed in some smaller towns throughout the history of Canada. Prior to 1900, almost all Chinese were located in British Columbia, but have spread throughout Canada thereafter. From 1923 to 1967, immigration from China was suspended due to exclusion laws. In 1997, the handover of Hong Kong to China caused many from there to flee to Canada due to uncertainties. Between 1881 and 1884, over 17, 0000 Chinese immigrants arrived in Canada to build the Canadian pacific Railway, and later to maintain it. Canada had about 25 Chinatowns across the country between the 1930s to 1940s, some of which have ceased to exist.