BABB, Mont. (AP) — On a cloudy spring day, hundreds lined up in their cars on the Canadian side of the border crossing that separates Alberta and Montana. They had driven for hours and camped out in their vehicles in hopes of receiving the season’s hottest commodity — a COVID-19 vaccine — from a Native American tribe that was giving out its excess doses.

The Blackfeet tribe in northern Montana provided about 1,000 surplus vaccines last month to its First Nations relatives and others from across the border, in an illustration of the disparity in speed at which the United States and Canada are distributing doses. While more than 30% of adults in the U.S. are fully vaccinated, in Canada that figure is about 3%.

Among those who received the vaccine at the Piegan-Carway border crossing were Sherry Cross Child and Shane Little Bear, of Stand Off, about 30 miles (50 kilometers) north of the border.

They recited a prayer in the Blackfoot language before nurses began administering shots, with Chief Mountain — sacred to the Blackfoot people — rising in the distance. The prayer was dedicated to people seeking refuge from the virus, Cross Child said.

Cross Child and her husband have family and friends in Montana but have not been able to visit them since the border closed last spring to all but essential travel.

“It’s been stressful because we had some deaths in the family, and they couldn’t come,” she said. “Just for the support – they rely on us, and we rely on them. It’s been tough.”

More than 95% of the Blackfeet reservation’s roughly 10,000 residents who are eligible for the vaccine are fully immunized, after the state prioritized Native American communities — among the most vulnerable U.S. populations — in the early stages of its vaccination campaign.

The tribe received vaccine allotments both from the Montana health department and the federal Indian Health Service, leaving some doses unused. With an expiration date fast approaching, it turned to other nations in the Blackfoot Confederacy, which includes the Blackfeet and three tribes in southern Alberta that share a language and culture.

“The idea was to get to our brothers and sisters that live in Canada,” said Robert DesRosier, emergency services manager for the Blackfeet tribe. “And then the question came up – what if a nontribal member wants a vaccine? Well, this is about saving lives. We’re not going to turn anybody away.”

The tribe distributed the Pfizer and Moderna vaccines over four days in late April at the remote Piegan Port of Entry, amid a backdrop of rolling grasslands to the east and Glacier National Park’s snow-covered peaks to the west.

As news of the effort spread in Canada, first by word of mouth, then through social platforms and media reports, people traveled from farther away. Some drove five hours from the city of Edmonton.

The effort was particularly timely as Alberta sees a surge in new cases of the respiratory virus, with a caseload record reached this month.

Bonnie Healy, Blackfoot Confederacy health administrator, said she was glad the vaccination effort reached both First Nations and other communities in the province.

“We have family members that live in those areas,” she said. “If we can get these places safe, then it’s safe for our children to go to school there. It’s safe for our elders to go shopping in their stores.”

Canadians who got the vaccines were not allowed to linger in the U.S. They returned home with letters from health officials exempting them from the mandatory 14-day quarantine imposed on all those entering the country.

The tribe’s initiative is one of a few partnerships that have cropped up between communities in the U.S. and Canada, where residents might otherwise have to wait weeks or months for a shot.

Canada has lagged in vaccinating its population because it lacks the ability to manufacture the vaccine and like many countries has had to rely on the global supply chain for the lifesaving shots.