The Standing Rock Sioux and other Native American tribes in North Dakota are rushing to get new voter IDs to members after the Supreme Court earlier this month upheld a lower court ruling supporting a burdensome election law.

That meant that, just weeks before the midterm elections, every voter in North Dakota suddenly needed to have identification with a street address — which tribes had challenged in court as discriminatory. Native Americans on reservations in the state rarely have addresses in remote areas with no street names, so the law is a particular challenge for them. Home locations are often described using landmarks, such as natural features, schools or businesses, and residents rely on post office boxes for mail.

“Voter suppression is a very real thing,” said Standing Rock activist Chase Iron Eyes. But it’s a testament to the power of the vote that “they’re trying so hard to suppress it. When you suppress a people, they rise.”

North Dakota is the only state in the nation without voter registration, and for years if there was any problem, residents only had to sign an affidavit saying they were eligible to vote. That was changed by the Republican state legislature.

The refusal of the nation’s top court after a challenge by the tribes now threatens to disenfranchise thousands of North Dakota Native Americans amid an extremely tight Senate race between Democratic incumbent Heidi Heitkamp and GOP challenger Rep. Kevin Cramer.