The museum, which is being built in Winnipeg, is asking same-sex couples from across Canada to submit their marriage photos online.
A selection of the photos will become part of the same-sex marriage exhibit, which will be part of the Canada's Journey gallery when the museum opens.
"Part of the work of the museum is to identify objects and artifacts that help convey and tell the stories of the museum," said Angela Cassie, a museum spokesperson.
"Sometimes, we need to put out a call to the public in order to identify and find those stories."
Rick North, a longtime gay-rights activist in Winnipeg, says it's hard to believe an exhibit dedicated to same-sex marriage would be part of any museum 40 years ago.
"We were delighted. It's wonderful to see the museum taking a leadership role on gay rights … the great civil rights struggle of our time," he said.
North said he and his husband are providing the museum with their marriage certificate. Granted by the Unitarian Universalist Church of Winnipeg in 1974, it was one of the first same-sex marriage certificates issued in Canada.
Those who want to submit their photographs to the museum have until March 15.