1996 Western North America blackouts

The 1996 Western North America blackouts were two widespread power outages that occurred across Western Canada, the Western United States, and Northwest Mexico on July 2 and August 10, 1996. They were separated by six weeks and were believed to have been similarly caused by excessive demand during a hot summer.

Source: Wikipedia — 1996 Western North America blackouts (CC BY-SA 4.0)