YOSEMITE VALLEY, Calif. — Gone were the massive granite monoliths of Half Dome and El Capitan, lost in the shroud of a ghostly and acrid layer of smoke. Gone, too, were the cascading waterfalls that plunge to the floor of Yosemite Valley, their famed beauty uselessly out of sight.

Most eerily, gone were the people. The iconic valley, usually smothered in tourists this time of year, was instead blanketed in plumes from a raging nearby 38,000-acre wildfire that forced evacuations and turned one of the country’s most popular national parks into a virtual ghost town on Wednesday afternoon. The closing is the largest in nearly three decades at the park.

Visitors were given until noon to leave. An hour later, the usually teeming cafeteria was dark, its chairs on the tables. Parking lots were empty. Campgrounds were cleared. The front door of the famous Majestic Yosemite Hotel, best known as the Ahwahnee, was padlocked with a chain.

The Ferguson Fire, which is encroaching on Yosemite Valley, is just one of some 75 large fires stretching from Oklahoma to Alaska, according to the National Interagency Fire Center, already costing millions of dollars. Thousands of firefighters are battling blazes in Arizona, Colorado, Idaho, and Oregon in what is on track to be one of the hottest summers on record for much of the region.