In the process, Polis becomes the third member of the LGBT community to win a gubernatorial nomination this year — the first time in American history more than one openly LGBT person has won a nomination in any given year.

But his nomination is historic nonetheless, in a year in which more gay, lesbian, bisexual and transgender candidates than ever before are running for office.

But he is not the first LGBT person to secure a spot on the November ballot this year. In Oregon, Gov. Kate Brown (D), the first openly bisexual person to serve as governor of any state, is heavily favored to win a full four-year term. Texas Democrats nominated former Dallas County Sheriff Lupe Valdez (D), the first lesbian to win a gubernatorial nomination.

Valdez faces a much steeper climb against Texas Gov. Greg Abbott (R). Polls show Abbott leading by a wide margin, and Abbott has socked away more than $40 million for the sprint to Election Day.

Their wins hint at the progress LGBT candidates have made in the decade and a half since the nation's first gay governor, New Jersey's Jim McGreevey (D), used the carefully poll-tested phrase "I am a gay American" in the same speech in which he resigned his office in the midst of a scandal.

In his own political career, Polis has had the benefit of his own bank account to back him up. He built his fortune by founding several internet-based businesses, and he has spent freely on his own campaigns since entering public life in 2000, when he won election to Colorado's state Board of Education.

Polis has dropped at least $10 million into his bid to replace term-limited Gov. John Hickenlooper (D) so far this year. He used that money to outlast former state Treasurer Cary Kennedy (D), former state Sen. Mike Johnston (D) and Lt. Gov. Donna Lynne (D) on Tuesday .

With 82 percent of the precincts reporting, Polis had taken 45 percent of the vote. Kennedy was running in second position, with 25 percent of the vote. The Associated Press projected Polis would win.