BOISE, Idaho -- The West may have been won a century ago, but the battle over how it will look a century from now continues, with property-rights initiatives on the ballot in four Western states.

Measures in Idaho, Arizona, California and Washington ask voters to follow the lead of Oregon, where residents in 2004 enacted a law that would force local governments to pay private property owners if new regulations reduce their land's value.

Aiming to capitalize on anti-government sentiment kicked up by a 2005 U.S. Supreme Court case in Connecticut, proponents say these ''regulatory takings'' measures protect people's freedom to profit from their land.

Opponents point to Oregon, where Measure 37 has resulted in more than $4 billion in claims. They say these initiatives are financed by wealthy ideologues bent on preventing local governments from deciding where subdivisions, gravel pits, even rendering plants can be built.

It's the latest collision of the Old West, where property rights border on the sacred, and the New West vision of a landscape that requires laws to shape and protect it appropriately. And it has attracted deep-pocket backers on both sides: Millions from conservative activist and New York real-estate mogul Howard Rich are propping up the ballot measures, while Paul Brainerd, Seattle-based founder of Aldus software, has injected at least $120,000 into the fight to shoot them down.

''I don't believe that developers should profit from dodging local land-use regulations,'' said Brainerd, who also owns a home near Ketchum, Idaho. ''Each community should be able decide how to best balance the rights and responsibilities of landowners to the greater community good -- not just the rights of an individual who wants to develop a subdivision with 250 homes on 20 acres.''

Laird Maxwell, the conservative activist pushing Idaho's Proposition 2 almost solely with Rich's money, said foes have employed ''esoteric, pie-in-the-sky scare tactics'' to frighten voters on Nov. 7. Proposition 2 is simple, he said: If government changes laws to limit how people can use their land, it should pay for the damage.

''This is for the little guy,'' Maxwell said, adding passage may eventually lead to more innovative community planning, including land swaps. ''They're messing with people's land -- and their dreams and their hopes -- and there's a lot of people who aren't going to take it lying down.''

''It is a battle over whether or not individual liberty will continue in the United States or not,'' Rich, also on the boards of the conservative Cato Institute and the Club for Growth, told The Associated Press. ''The opposition are government bureaucrats, those that profit from taking other people's property without paying for it, and those that have radical agendas hidden under soft facades.''

There could have been more measures: A Montana effort appears dead after a judge found signature-gathering fraud got it on the ballot. And the Nevada Supreme Court trimmed regulatory-takings provisions from a measure there.

As the West grows and changes, battles emerge in part because some fear they'll be left behind.

''Landowners see zoning laws as an obstacle to them transitioning out of resource use and into urban development,'' said Sy Adler, an urban studies professor at Portland State University and co-author of ''Planning a New West.'' ''It would be nice to do this in a more planful way rather than a ballot-measure approach.''

Proponents say that's the only way to get government to listen.

Ed Terrazas, an architect near Sun Valley, Idaho, signed onto Proposition 2 after the local government rejected his plan to build four homes on 115 acres of sage and grass he owns above the Big Wood River, near where it flows out of the Rocky Mountains.

''Largely from my years of planning experience, I've seen other people harmed by overzealous regulation that doesn't account for property rights,'' said Terrazas, who is suing Blaine County. ''You're fighting your own government, and they have unlimited resources.''

Some of the ballot measures are married to provisions meant to address eminent-domain abuse fears that arose after the 2005 U.S. Supreme Court decision in Kelo v. New London. The Connecticut city was allowed to condemn residential property to clear the way for a private development.

Still, foes in Idaho, including business groups, cities and counties, and Republican Gov. Jim Risch, say eminent domain is no longer a concern, since state lawmakers this year passed new laws greatly restricting when governments can seize private property.

Others argue the regulatory-takings measures would produce a system where land-use disagreements will wind up in courts, costing taxpayers millions. Or, costly lawsuits might prompt some communities to simply allow poor development to go ahead.

''What we've got is this out-of-state sugar daddy who is supporting this far-out proposition that will put Idaho communities at risk,'' Dan Chadwick, Idaho Association of Counties director, said of Rich.

It's no surprise private-property measures have emerged in the West, home to some of America's fastest-growing states. Nevada was No. 1 in 2005, followed by Arizona and Idaho.

''I would be interested to see whether there's an effective resistance that can be mounted to this kind of initiative,'' said Dan Kemmis, a senior fellow at the Center for the Rocky Mountain West at the University of Montana.

''There's a growing perception in many of these places that if the West is going to prosper in the long run, and not just make a quick buck out of rapid growth for a short time, that we've got to be as smart as we can be in controlling our own destiny.''