Timeline: Michael Sam and 40 years of LGBT rights in sports

Before Michael Sam, there was David Kopay.

In December 1975, Kopay read a series in the Washington Star on the everyday struggles of being a closeted gay athlete in pro sports. Kopay, who had retired from the NFL three years before, recognized one of the individuals featured, although his name wasn't given. It was his former teammate and lover Jerry Smith. 

An enormous amount of hate mail flooded the Star, and Kopay learned that most of it claimed there was no way gay players existed in the NFL. So that same month, Kopay decided to be profiled in the Star himself, becoming the first former NFL player to be openly gay. 

Kopay has been a pillar in the LGBT community's fight for equal rights in sports for nearly four decades. But even with the recent progress made by LGBT athletes such as Jason Collins and Robbie Rogers, there was a sense that the push for an active, openly gay professional athlete in a major American league had turned stagnant.

“There really hasn't been that athlete to come out that's still playing. And it's been so long," Kopay told OutSports.com in 2011. "I thought it would happen. I didn't know if I thought it would happen in 10 years or 20 years, but 36 years? That doesn't make any sense."

Support for Sam, who is set to be the first openly gay player in the NFL when he's selected in May's NFL Draft, among professional and college players has been overwhelmingly positive, but there remains some skepticism on how his coming out will affect the culture of whatever team he will be playing for on Sundays this fall. 

With Sam poised to make history, America Tonight looks back at some of the highs and lows in the the struggle for LGBT equality in sports in the last 40 years.