LeRoy Comes Last and his family live on a hump of benchland in northeastern Montana, on the Fort Peck Indian Reservation. In all directions the land is flat and treeless, with just a few soft ridges here and there, as if someone lay sleeping beneath the topsoil. To the south, U.S. Highway 2 cuts toward the town of Poplar in one direction and Wolf Point in the other. Just beyond lie the tracks of the Great Northern Railway, where passenger trains with names like Empire Builder once ran. And farther still, yellow cottonwoods mark the course of the Missouri River, the reservation's southern boundary.

Inside the Comes Last mobile home, toddlers -- the charges of a daughter-in-law who runs an ad hoc daycare center -- careen around the living room under streamers of black and orange Halloween crepe. Seated at his kitchen table, his rough hands resting on a plastic tablecloth decorated with cartoon spiders, Comes Last looks as if he might have wandered into the wrong home. A tall man in his 60s, he has a warm weathered face and a purple neckerchief, and wears his hair in long braids under a black cowboy hat. His young round-cheeked Northern Cheyenne wife, Sabrina, sits next to him, holding a child.

"I always say I stole her," Comes Last chuckles. "I still owe her dad seven pinto horses."

Comes Last is a full-blooded Lakota Sioux of the Hunkpapa Band. His ancestors arrived at Fort Peck more than a century ago. His business card proclaims him a "Holy Dog Consultant," spiritual leader and firestarter, and he is one of the few remaining Lakota speakers on the reservation.

The acrid scent of a smudge stick wafts into the kitchen as a sleepy 3-year-old boy with gravity-defying black hair wanders through. "Ice cream," the boy says plaintively. "Ice cream." 

"It's the man of the hour!" cries Comes Last, patting his grandson on the shoulder.

Ryan Padraza Comes Last is a full-blooded Indian, Sioux and Cheyenne on his father's side and Assiniboine on his mother's. He will soon receive his Lakota name: "A Rope." (Comes Last raises rodeo horses and always has a rope in his right hand. He likes to call Ryan his "right-hand man.") But despite his traditional roots and his Native heritage, Ryan may be one of the last of the Comes Last line allowed to enroll as a member of the Fort Peck Tribe.

According to the tribal Constitution, enrolled members must be at least one-quarter Assiniboine or Sioux, or a combination of the two. (Fort Peck is home to both groups, who share one government.) This method of measuring Native American ethnicity by percentage is known as the "blood quantum," and most Indian tribes use it to determine who can be admitted. A few use a different method, called "lineal descent," under which applicants need only prove they have an ancestor on the early tribal rolls. Before 1960, Fort Peck used lineal descent as well.

In general, Native Americans cannot enroll in more than one tribe at a time, and for those tribes that require a particular percentage of Native blood, the parameters vary. For instance, by Fort Peck's rules, Ryan Padraza's blood quantum is only three-quarters. This is because his Cheyenne blood does not count at Fort Peck.