NACO, Ariz. — Thousands of American troops swarmed here long ago, a response to border friction of a different era. A visible reminder of that turbulent 1911-1923 timeframe — the stucco-walled barracks and officers quarters of Camp Naco — has been placed on the Arizona Preservation Foundation’s 2007 Most Endangered Historic Places list. “All of the properties we have named are important historic landmarks in Arizona, but unfortunately are in grave danger of collapse, demolition, or destruction,” said Vince Murray, president of the Arizona Preservation Foundation board. “It is critical that residents and government officials act now to save these...