Australia, home to the first Earth Hour last year, comes in a distant second, with 10 participating municipalities, while the U.S. has nine.
But there's still time to join, and World Wildlife Fund organizers anticipate the numbers will increase.
"We're completely amazed by the response in Canada," said Tara Wood, spokesperson for WWF-Canada, adding she couldn't explain the overwhelming flood of environmental consciousness being shown by Canadians.
"We thought we'd roll out (Earth Hour) in Toronto and see what happened. It's taken off across the country in a grassroots way."
The first Earth Hour was held in Australia in 2007 and organized by the local WWF. An estimated 2.2 million Australians participated, reducing demand on the power grid by 10 per cent.
It may not be a solution to global warming, "but it's a step," Wood noted. "And it lets people see how individual actions add up. Earth Hour is a great celebration of what we can accomplish together and it gets us thinking about simple steps we can take to make every hour Earth Hour."
Turning off unneeded lights and appliances and changing to energy-saving bulbs could cut annual emissions by 5 per cent, Wood said.
A similar highly successful program called Lights Out was launched in San Francisco last year. Organizers have harnessed growing interest in energy conservation across the U.S. with a national initiative, Lights Out America. An LOA event had been scheduled to coincide with Earth Hour, but organizers have now joined the global event rather than doing it on their own.