The U.S. border inspector at this lonely desert crossing with Mexico fingers the tribal enrollment card decorated with a wooden staff and eagle feathers, and glances at the holder's photograph.
Tohono O'odham elder Ofelia Rivas, 51, has used the document to cross between the tribe's ceremonial sites in Mexico and her home in Arizona for years, but the inspector tells her that it will soon no longer be valid for international travel.
The U.S. Western Hemisphere Travel Initiative in January will require U.S. citizens to present government photo ID, such as a driver's license, plus proof of citizenship, such as a birth certificate, when they enter the United States by land or sea.
The measure, which is to be followed by requirements for a passport by June 2009, is causing confusion and anxiety among some Native American tribes that straddle the United States' borders with Mexico and Canada.
According to the National Congress of American Indians, there are around 40 U.S. tribes whose members cross regularly over the northern and southwestern borders, some to work and visit kin, others to attend ceremonies at traditional sites.
With implementation of the new travel rules looming in just a few weeks, some tribal members say it is still unclear whether enrollment documents issued by their own tribal governments will be acceptable at the borders, and are unsure if they can meet the new travel ID requirements if they are obliged to comply.
"We were all born at home with a midwife, and nobody at the time recorded our births," said Rivas, explaining the difficulty for her and other members of her family who cross frequently to and from Mexico using their tribal enrollment cards.
"I have no birth certificate so how am I supposed to get a passport?"
The U.S. travel initiative kicked off in January this year, when all people traveling between the United States and Canada by air were required to present a passport to enter or re-enter the United States.
The second phase for land and sea travel comes into effect on January 31 2008. It will be followed by tougher rules requiring all U.S. citizens to hold passports or new "passport cards," created for limited cross-border travel, by June 1 2009.
The impending changes will affect traditional nations including the Confederated Colville Tribes, the Blackfeet and the Mohawks, who cross back and forth across the northern border with Canada, as well as several tribes who travel between Alaska and British Columbia and the Yukon Territory.
Southwest border tribes affected include the Tohono O'odham, in Arizona and Sonora, the Campo Band of the Kumeyaay Nation who have members in California and in Baja California in northwest Mexico, and the Kickapoo Band of Texas and Tribe of Oklahoma, who have ties to kin in Coahuila, Mexico.
The new passport rules make exceptions for some travelers including cruise ship passengers embarking from and returning to U.S. ports as well as U.S. and Canadian children traveling in designated groups, who will not be required to show passports for travel.
But so far, the Kickapoo are the only tribe authorized to cross over the border using their American Indian Cards instead of a passport, under a special law that was passed in the early 1980s.
Several border tribes are in talks with the U.S. Department of Homeland Security individually to discuss the status of tribal enrollment cards, yet it remains unclear what arrangement they might reach.
"It's very confusing. Nobody except for the DHS staff who are writing it right now knows what the final law is going to look like," said Heather Dawn Thompson, the Director of Government Affairs at the National Congress of American Indians.
The U.S. government recognizes several hundred Native American nations whose members lived on the land for centuries before the United States, Canada and Mexico existed, speaking their own languages and following beliefs centered on the natural world.
A spokeswoman for U.S. Customs and Border Protection told Reuters that Native Americans will be able to continue presenting tribal enrollment cards if they are affixed with a photo ID during the transition period from the end of January.
Kelly Klundt said the challenge remains in ensuring that all tribal enrollment documents have adequate security features to comply with the new requirements, and that tribes can demonstrate that the issuing process is secure.
"We are working with the tribes to see what solutions we can come up with that will meet the security requirements while recognizing their cultural and historical needs," Klundt said.
"It is very high on our radar, and we are very cognizant of their specific concerns," she added.
But despite assurances that tribal ID documents will continue to be valid for travel, the situation on the southwest border is confused.
While crossing north from Mexico through Lukeville with this correspondent late last month, Rivas was told by a CBP inspector she would need a passport to cross from January.
Rivas said that the lingering uncertainty over Tohono O'odham members' ability to visit family and carry out sacred ceremonies at Quitovac in Mexico haunts her and other traditionalists in the tribe.
"The elders are distraught that they might not be able to go and conduct a ceremony that we have carried out since Creation," she said. "It is devastating. I can't imagine not going."