SALT LAKE CITY — Nearly two dozen counties are joining the state of Utah in lawsuits challenging the federal government's control of thousands of dirt roads that primarily cross rural parts of the state.

So far, about half of the lawsuits have been filed while the others are expected to be filed in U.S. District Court in Salt Lake City this week.

Thirteen counties filed lawsuits within the last week, including Beaver, Box Elder, Carbon, Daggett, Duchesne, Emery, Millard, Piute, Rich, Sanpete, Sevier, Utah and Wayne counties. Kane and Garfield counties filed lawsuits last year.

When combined, the lawsuits will seek control of more than 12,000 routes. Originally, the state was considering laying claim to more than 18,000 routes but has reduced that number as they have evaluated the worthiness of individual rights-of-way.

"These actions will preserve access for Utah families to continue to use the roads that they have used for decades," Chief Deputy Attorney General John Swallow said.

Swallow said the state "has been forced into this process of litigation" because the federal government has been closing routes that were used for generations.

Representatives of the Southern Utah Wilderness Alliance and the Sierra Club have criticized the legal fight, saying it could cost the state millions of dollars in legal fees and lost tourism revenue.

The groups also say the increased vehicle access would degrade important habitat for mule deer and sage grouse, and lead to more vandalism and theft at sensitive archaeological sites.

Last month, a coalition of environmental groups issued a map that shows the state is trying to claim management routes that cross Utah's rugged backcountry, national parks and wilderness areas.

The lawsuits are part of a decades-long dispute throughout the western United States, as states seek to gain access to federal lands for uses ranging from outdoor recreation to mining. The contested routes can range from graded dirt roads to dry stream beds.

County and state officials argue access should be maintained on these roads because they are important routes for traveling in rural areas of the state and they provide access to the outdoors.

They also maintain the roads should be accessible because they were used for at least a decade before the federal government closed them.