VANCOUVER - Prime Minister Justin Trudeau is about to become the first sitting prime minister to march in Vancouver's annual pride parade.

The Vancouver Pride Society says today's parade is expected to attract more than 500,000 spectators.

Trudeau is already a veteran of the festivities, having marched in the parade in 2014 and 2015 as leader of the Liberal party.

His participation in today's event follows the milestone he set earlier this month when he became the first sitting prime minister to march in Toronto's Pride parade -- the country's largest.

The revellers in Toronto, some decked out in rainbow gear and outlandish costumes, gave the prime minister a boisterous reception, posing for selfies with him and chanting his name as he passed by.

Trudeau, however, downplayed his appearance at the July 3 parade as no big deal, noting he'd been attending Pride parades for years.