At this point, Kennecott Land has no stated preferences as to the jurisdiction of its future developments — whether they remain parts of unincorporated Salt Lake County, are annexed into existing cities or if new cities will be formed. County planning director Jeff Daugherty said the county hopes to adopt plans and principles that will be flexible and can follow the development no matter whose control it ends up under.

The plan has received preliminary support from the dozens of summit participants who watched the plan evolve and gave input in recent months. Its backing by so many interests comes from Kennecott Land's unique process and specific ideas, McMahon said.

"We've been able to paint a vision," he said. "We've sort of captured their imaginations a bit."

The planning has often centered around concepts promoted by Envision Utah, a public-private group pushing for "smartly planned" growth. Though Envision Utah is not a partner in Kennecott Land's plans, the organization is watching them closely.

"From our perspective there are still issues to be addressed, but we think it's admirable that a private landowner would go to extraordinary lengths to make sure that its project meets the long-term transportation, environmental needs of the region," Envision Utah executive director Alan Matheson said. "It's early in the process so we want to continue to communicate with them in finding solutions that will work for this area. We're talking still 70 years out, and a lot can happen in that time. But I think we're fortunate to have a company willing to put in the resources" to plan from the beginning.

But not everyone is eagerly awaiting the development.

Lying in the mouth of Bingham Canyon, near Kennecott Utah Copper's massive copper pit, is the township of Copperton, a quiet, unincorporated little piece of Salt Lake County that residents worry is on the verge of big changes, spurred largely by Kennecott Land's plans.

They worry that nearby cities will seek to annex Copperton, while most residents there want the area to remain unincorporated. And they worry about the commotion and chaos of suburban sprawl moving closer to their doorsteps.

"What's around us we really can't control, but we want to keep our community intact the way it is," Town Council chairman Jerry McCalmon said.

The environment

One of Kennecott Land's stated principles is environmental sustainability, and McMahon said Rio Tinto's commitment to environmentally friendly policies was a big reason the company decided to keep control of the development rather than selling it off.

Kennecott's plans call for a focus on walkability and mass transit, as well as sustainable energy use, water conservation and maintaining about 30 percent of the developed land as open space.