(CNN) South Bend Mayor Pete Buttigieg entered the 2020 race for president on Wednesday, announcing his intentions with a video featuring scenes of him and his husband, Chasten, cooking and playing with their dog, Buddy.

Should Buttigieg win his long-shot bid for the Democratic nomination, he will become the first nominee of a major political party who publicly identifies as gay. If he goes on to defeat President Donald Trump, it'd be a historic win.

This appears unlikely (but by no means impossible) at this point; Buttigieg is not very well-known outside of Indiana and he's entering a crowded field of more established contenders. That a gay married man is running a serious campaign for president, however, is a big deal, and we shouldn't let the improbability of his candidacy stop us from acknowledging this moment.

Only a decade ago, his run would have been unthinkable.

Gay marriage was legal in only two states in January 2009 -- Massachusetts and Connecticut. Voters in California -- one of the most Democratic states in the country -- had just passed Proposition 8, banning same-sex marriage in the state. Barack Obama became President, and although he was supportive of expanding legal rights for the LGBT community and gay couples, he was on the record during his campaign as being opposed to same-sex marriage.

"I believe marriage is between a man and a woman. I am not in favor of gay marriage," Obama told MTV News during the 2008 campaign.

It would have been fair to think that progress would come slowly for the LGBT community if even Obama, who was considered to be a progressive within the Democratic Party on many critical issues, was publicly opposed to same-sex marriage at the time. But the next eight years of his presidency saw rapid change.

In 2010, President Obama signed into law the Don't Ask, Don't Tell Repeal Act, ending a policy enacted in 1993 that prevent gay men and lesbians from serving openly in the military. In 2012, in the heat of a presidential campaign, Obama became the first sitting US president to support same-sex marriage, telling ABC News, "At a certain point I've just concluded that for me, personally, it is important for me to go ahead and affirm that I think same-sex couples should be able to get married."

Three years later, the Supreme Court ruled that states cannot ban same-sex marriage, making it legal nationwide for gay and lesbian couples to marry.

Public attitude shifted as well. In 2009, 54% of Americans opposed same-sex marriage and only 37% supported it, according to Pew Research Center. By 2017, that number had flipped: 62% of Americans supported same-sex marriage, while only 32% opposed it.

And during this time, candidates who publicly identify as gay, bisexual and transgender have broken barriers with their wins. In 2012, Wisconsin's Tammy Baldwin became the first gay person elected to the US Senate (she was re-elected in 2018). Kate Brown became the first bisexual governor in the US in 2015 when she was appointed in Oregon. She has been elected twice since then.

In last year's midterm elections, Colorado's Jared Polis became the first gay man in the US to be elected governor, Kyrsten Sinema, who is bisexual, won a US Senate seat in Arizona, and Sharice Davids, a lesbian, won her US House race in Kansas.

All of this is to say, quite simply, that in a relatively brief period of time, the politics surrounding gay marriage and LGBT equality shifted dramatically. And even though issues surrounding LGBT equality are hardly settled, Buttigieg's announcement is a good reminder of the progress that has been made.

Buttigieg, who was elected mayor in 2011 at the age of 29, came out in 2015 -- days before the Supreme Court struck down same-sex marriage bans nationwide. In a column titled 'Why coming out matters," he wrote about the difficulty he had coming to terms with his sexuality and being open about it publicly.

"We Midwesterners are instinctively private to begin with, and I'm not used to viewing this as anyone else's business," he wrote. "But it's clear to me that at a moment like this, being more open about it could do some good. For a local student struggling with her sexuality, it might be helpful for an openly gay mayor to send the message that her community will always have a place for her. And for a conservative resident from a different generation, whose unease with social change is partly rooted in the impression that he doesn't know anyone gay, perhaps a familiar face can be a reminder that we're all in this together as a community."

Buttigieg might not have a real chance at winning the Democratic nomination. But by announcing he is running for the highest office in the land with a video that features his husband, he's already on the path to accomplishing what he set out to do in his column.

He acknowledged as much to CNN's Dan Merica on Wednesday, saying, "I am also mindful of the fact that this just might make it a little easier for the next person who comes along. My sincere hope is that by the time my kids are old enough, once we have kids, to understand politics, that it won't even be newsworthy."

And who knows. Maybe he'll make the debate stage. Maybe he'll take off in Iowa, and that momentum will propel him further than we can foresee now.

But one thing is for sure: Having a gay candidate -- or nominee, or president -- is no longer such a farfetched idea.