Oregon Trail is on the road to ruin, some fear : Development is wiping away the historic route, but a preservation movement is gathering steam.

In the 1800s, wagon wheels dug into the soil as thousands of pioneers headed west on a tortuous journey that helped settle the Oregon Territory.

The 2,170-mile route from Independence, Mo., to the fertile Willamette Valley became known as the Oregon Trail, a deeply rutted path that was followed by 50,000 people seeking a better life.

People are still trying to improve their lives along the trail, but often the only vehicles around these days are bulldozers and earthmovers clearing the way for housing developments.

And that upsets people such as Mildred Hall.

Even though she sells real estate for a living and she lives in a 12-year-old Idaho subdivision named Oregon Trail Heights--where houses sit on and along the Oregon Trail--Hall has joined a growing movement to preserve the Oregon Trail and the California Trail, which branched off from it.

Hall says that when she moved in a decade ago, she didn’t know her subdivision was sitting on the Oregon Trail.

But she knew she was a descendant of pioneers, and she has the genealogical charts and other memorabilia to prove it. Her great-grandparents, Asa and Anna Abbott, left Missouri in 1853 and labored across the trail, their covered wagon jostling and bouncing along the same ruts now flattened beneath a house just down the street.

Like Hall, many preservationists and county officials here have only recently become aware of the trail’s precise location. Much of the historic route has been obscured by years of farming, highway-building, vandalism and indifference.

“In the past, there has been minimal concern and thus considerable desecration along the trail because people haven’t known or cared,” said Eugene Potter of Casper, Wyo., a preservation officer with the Oregon-California Trails Assn.

Besides the development controversy here, a handful of other proposals have served to rally preservationists, history buffs and others along the Oregon Trail in recent years.

Currently, some residents and the congressionally-chartered National Trust for Historic Preservation are fighting a Canadian company’s plan to install an underground gas pipeline near the trail at Wyoming’s South Pass, a milestone that signaled the beginning of the Oregon Territory to weary pioneers. In the recent past, there has been concern over the building of Interstate 80 in northeast Nevada.

“However, the most unfortunate occurrence has been the vandalism by other travelers and souvenir hunters,” wrote William E. Hill, a high school history teacher in New York state and author of books about historic Western trails.

“Some locations have been vandalized so much that owners do not encourage or even allow visitors to enter.”

Most of the worry about safeguarding the trail has been focused on its western half because much of that section is on public land and because farmers on the eastern end, particularly in Nebraska and Kansas, obliterated virtually all the trail’s ruts and markings after the turn of the century.

Today, the two main battlegrounds in the effort to preserve the Oregon Trail are in Wyoming’s South Pass and in Boise.

“If it goes through, it’s gonna stick out like a sore thumb,” said Tom Bell, a Fremont County, Wyo., historian fervently opposed to the gas pipeline proposed for South Pass.

Pipeline supporters, including some preservationists, say the 30-inch pipeline can be built with minimal impact.

To wage their fight, opponents in Wyoming are invoking federal laws and pursuing hearings before the Federal Energy Regulatory Commission.

In Boise, though, a dearth of local zoning laws means that opponents of the housing development have few legal grounds to stop the eventual construction on land owned by Idaho’s richest man, potato magnate J.R. Simplot.

Consequently, activists such as Hall can seemingly do little more than write to the governor and the mayor.

For now, developer Al Marsden has withdrawn--some say only temporarily--plans to build on the trail, apparently preferring to concentrate on other portions of the 700-home development.

A Marsden spokesman, consultant Chris Korte, dismisses suggestions that the developer has been insensitive to the property’s historical significance, adding that if the land is so important, “the community ought to purchase it.”

Korte, not ruling out future construction on the trail site, said that with so many sub-trails and alternate routes off the main trail, it is likely that some area of historical importance eventually will have to be “sacrificed” to accommodate Boise’s growing housing market.

“There are Oregon Trails within the Oregon Trail,” he said. “Some places with one rut, two ruts, 10 ruts, they (pioneers) went down to the river here, they went down to the river there. . . .

“Everybody has to give a little bit.”