Some of the new owners have been welcomed. The cable magnate, John Malone, for instance, has been praised by the Nature Conservancy for his family’s conservation efforts, and other buyers have helped to clean up trails and restore pristine acres.

The arrival of this new class of landholders comes as the region is experiencing the fastest population boom in the country, which is driving up housing prices and the cost of living and leaving many residents fearful of losing their culture and economic stability.

In Idaho, Rocky Barker, a retired columnist for The Idaho Statesman, has called the conflict a “clash between two American dreams,” pitting the nation’s respect for private property rights against the notion of a beauty-rich public estate set aside for the enjoyment of all.

The clash, he said, is part of a larger transformation of the region — from an economy rooted in extraction to one based on recreation; from a working class culture to a more moneyed one. “Big landowners,” he said, “are just another new force.”

The Gate

Tim Horting is among the people caught up in the debate. Mr. Horting, 58, a heavy equipment salesman, grew up hiking in the woods north of Boise, a forest threaded by dirt routes that offer views of the state’s celebrated peaks. He learned the terrain from his father, who taught him to chop wood, gut deer and haul game home for dinner.

Mr. Horting and his wife, Kim, built a cabin in those woods in 2006, right by Boise Ridge Road, which led to a popular recreation area built mostly on public land. The Hortings said they wanted their grandchildren to grow up with a feel for rural life. “This is the whole reason I moved here,” Mr. Horting said. For years, he assumed the road was public, and he would guide his ATV up its steep ascent, his grandchildren in tow.