SALT LAKE CITY — A lawsuit filed by members of the Navajo Nation who say mail-in voting in southern Utah disenfranchises tribal voters is headed for trial.

U.S. District Judge Jill Parrish set a March 16 trial date Thursday in the case filed by The Navajo Nation Human Rights Commission and the American Civil Liberties Union of Utah.

Mail-in ballots are harder for Navajo voters to receive because many don't have mailboxes and can be difficult to use for people who speak Navajo, said John Mejia with the ACLU.

A reduction in physical polling places also means people in rural areas might have to drive hours to reach an early-voting site, he said.

The county sits in the Four Corners region and covers the northern tip of the Navajo Nation that stretches into Arizona and New Mexico. More than 50 percent of people who are voting age in San Juan County are Navajo, Mejia said.

San Juan County officials argue that the new voting system has led to higher voter turnout. Officials also say that they have operated translator-equipped polling sites on Election Day closer to Navajo voters than white voters.

They have said the lawsuit was filed in an effort to sway local politics.

Similar legal clashes have been waged in Nevada, Montana and the Dakotas over a variety of issues involving the Voting Rights Act, including access to polling places as well as unreliable U.S. mail service on reservations.