Developers and Conservationists Battle Over National Parks In a long-running saga that underscores a broader battle over commercial construction in and around national parks, voters in this tiny community just south of the Grand Canyon have thwarted the latest proposal by hotel developers. Tusayan, with just 500 residents and 174 registered voters, last month narrowly defeated a motion to incorporate as a city, a move that would have given it property-zoning power. The outcome deals a setback to Gruppo Percassi, an Italian developer that long has coveted building permits for ranchland and other property it owns in the area. In 2000, a countywide referendum doomed Percassi's previous project: a $300 million hotel and shopping complex in Tusayan. The tussle near one of the world's natural wonders is likely to continue, and it isn't an isolated conflict. In suburban Philadelphia, conservationists are trying to stop a $250 million museum, conference center and hotel from being built on private land inside Valley Forge National Historical Park, site of George Washington's 1777-78 winter military encampment. Backers of the plan say the complex would be a premier Revolutionary War educational center, while opponents say the location would desecrate the site and result in harmful traffic and pollution. The National Parks Conservation Association, an independent nonprofit group that is leading the opposition at Valley Forge, says a growing number of the 391 U.S. national parks face commercial development threats. Some 4.3 million acres of land inside national parks are privately owned tracts that existed when park boundaries were drawn or expanded....