- By 1920, hydro accounts for more than 97 per cent of the electricity generated in Canada. As increasingly remote sites must now be developed, and thermal generation becomes more economically attractive, this percentage begins to fall.
- From 1921 on, electricity trade between Canada and the U.S. is to Canada's advantage.
- The first electric range, a Canadian invention, is built in 1921.
- In that same year, Ontario Hydro opens Sir Adam Beck No. 1, the world's largest power plant.
- With the introduction of refrigerators and washing machines in the 1920's, electric appliances for the home begin to multiply. By 1960, there are more than 80 different kinds in existence.
- The Canadian Electrical Code is adopted by the Canadian Standards Association in 1927.
- In 1928, the first 220kV transmission travels more than 440 km from Paugan Falls, Québec to Toronto.
- In the same year, Edmonton Power installs one of the world's first 10 MW turbo-generator, running at 3,600 rpm, at its Rossdale Plant.
- By mid-century, hydroelectric generation accounts for 90 per cent of total capacity, with thermal generation supplying the balance.