Events of National Historic Significance (also called National Historic Events) are events that have been designated by Canada's Minister of the Environment, on the advice of the national Historic Sites and Monuments Board of Canada, as being defining actions, episodes, movements or experiences in Canadian history. To be designated, an event must have occurred at least 40 years previous; events that continue into the more recent past are evaluated on the basis of what occurred at least 40 years ago. As of April 2015, there are 451 designated Events of National Historic Significance.