Members of the Osage Nation, a Native American tribe in northeast Oklahoma, on Monday voted to allow gay and lesbian couples to marry.

According to the tribe's paper, The Osage News, 52 percent of voters cast their ballots in favor of marriage equality.

The measure was authored by Osage legislator Alice Buffalohead.

Henry Roanhorse Gray created a Facebook group in support of the measure.

“I knew [the vote] was gonna be a huge challenge to get a typically conservative and religious electorate to pass marriage equality, so it being such a close race was no surprise,” Gray, the co-creator of the Facebook group Osage Citizens for Marriage Equality, told NBC Out. “It really shows the importance of voting – history was truly made by the ones who showed up.”

The United States recognizes more than 567 tribes as sovereign nations. As such, the Supreme Court's 2015 finding that gay couples have a constitutional right to marry does not extend to federally recognized tribes.

“Tribes don't have to follow Obergefell,” Robert Clinton, a professor in tribal law at Arizona State University's Sandra Day O'Connor College of Law, told Reuters. “Tribes should, unless they have a good reason not to.”

The Osage join only a handful of tribes that recognize marriage equality, including the Cherokee Nation and the Cheyenne and Arapaho Tribes.