Six gay couples have sued the state of South Dakota to marry, leaving North Dakota as the only U.S. state with a same-sex marriage ban that hasn't yet been challenged, according to the Associated Press.
The lawsuit follows a flurry of gay marriage rulings across the country in recent weeks, most of which have either struck down existing bans (such as in Idaho, Oklahoma, Virginia, Michigan, Texas and Utah) or ordered state officials to recognize existing same-sex marriages (Kentucky, Ohio and Tennessee).
The legal challenge also comes just one day after four Montana couples filed a similar lawsuit calling their state's ban on same-sex marriage into question. Montana passed a statewide referendum against gay marriage with 67% of the vote in 2004.
To date, 19 states and the District of Columbia have legalized same-sex marriage. Massachusetts was the first to do so, 10 years ago this past week.
Since the Supreme Court’s decision last summer to end the Defense of Marriage Act, which barred federal recognition of same-sex marriages, every single federal court to consider a ban has ruled against it.
"It doesn't matter whether you're first or last," Nancy Rosenbrahn told USA Today. "It's about sending a message to the country and the Supreme Court: Look at all these states; you can't ignore this."
Nancy and her partner, Jennie Rosenbrahn, are part of the lawsuit challenging South Dakota's constitution.
There are currently pending cases before the courts in 30 U.S. states challenging same-sex marriage bans. South Dakota's has been in place since 52% of voters passed it in 2006.
Eight years later, support for same-sex marriage is at an all-time high. According to Gallup, 55% of Americans now back marriage equality.
Still, South Dakota Attorney General Marty Jackley is committed to upholding the state's ban.
"It is my duty as attorney general, and case law supports, that traditional family values and definitions are determined by state law," Jackley said Wednesday. "And if there is going to be a change, then that change should come from the voters of South Dakota at the ballot box."