“A lot of people out here don’t even know that they have an allotment,” said Mr. Chavez, who lives on the Navajo reservation’s edge in New Mexico. “It was something their grandparents or parents had always taken care of, and they had no idea they had ownership of land.”

About half a million Indians are eligible for payments, which vary in amount from hundreds to tens of thousands of dollars, depending on how much income their land generated. More than 30,000 tribal members have not yet been located. Some may have moved or died or are unaware they are eligible. The government has simply lost track of others.

All are owed at least $800, and in many cases, thousands more. The total owed to missing beneficiaries is approximately $32 million, according to Kilpatrick Townsend & Stockton, a law firm that worked on the settlement and is involved in locating tribal members.

David Smith, a lawyer with the firm, said the large number of missing beneficiaries illustrated how the Indian land trust program, administered by the Interior Department, was mishandled.

“Historically, there is no question that the government mismanaged these accounts and should have known where these people were,” Mr. Smith said.