Even as visitation has been up at the iconic California park and across the national park system, time spent per visit in the parks has dropped - declining nearly 15% systemwide over the past two decades.
In places such as Yosemite, the drop-off is much greater. Park spokesman Scott Gediman said fewer people are making the park a destination for a week-long camping trip, instead choosing to cruise through the Valley seeing a few main sites for a few hours before heading elsewhere.
"The way the visitors are seeing the parks is totally changing," he said. "We'll see 70-80 buses come through, and maybe one or two of them are spending the night. More and more, people are not just coming here, they're going to other parks and places as well. We're finding that vacations themselves have changed."
The National Park Service trend bucks statistics showing that Americans are increasingly spending more time and money on outdoor recreation, said Avery Stonich, communications manager for the Outdoor Industry Association. Over the past five years, spending on outdoor recreation has increased by 5% annually, according to analysis by her organization.
"People are still making outdoor recreation a priority in their lives," Stonich said. "While they aren't going to the national parks, they certainly are spending more time outdoors."
At Yosemite, the average park visitor spent nearly 27 hours inside the national park in the early 1990s. By 2011, that was down to less than 17 hours. Many of the nation's largest parks have seen similar declines - in the Grand Tetons, Wyo., the hours the average visitor spent in the park dipped from 10 to about 6½ over the past two decades. At the Grand Canyon, hours spent were down 10%, and at Cape Hatteras, N.C., that figure had dropped more than 19%.
The hours-spent figure is an estimate determined by statisticians who assign a set number of hours to each visitor determined by what entrance they use, whether they stay overnight, and other activity factors.
The decline in overnight park stays is largely to blame for the decrease in time spent in the parks, officials said. Although National Park Service surveys don't specifically track why camping has dropped off, numbers show that the entire parks system saw 4.5 million fewer overnight stays in 2011 than it did at its height in 1994 - a 25% decrease.
"Everybody wants to know why camping in general is down. Frankly, we just don't know," said Butch Street, analyst for the National Park Service. One popular theory, he said, is that the decline is tied to the park systems' increasingly older visitor population - as baby boomers age, they may opt for a local hotel rather than roughing it in a tent.
"They just don't camp out," he said.
At Yosemite, flooding in the late 1990s wiped out campsites and lodging that still haven't been rebuilt. The limited lodging there is largely booked months in advance, Gediman said, but more visitors have chosen to make the park a day trip, or to stay in one of the communities just outside the park limits.
That means more traffic headed through towns around the park. This year for the first time, park rangers have been stationed at visitor centers in neighboring Mariposa, Oakhurst and Groveland to help tourists plan their trip, Gediman said. As more visitors want to spend less time seeing the sights, the midday rush has become a logistics dilemma, he said: Parking shortages and infrastructure are strained by a crush of people. The rangers advise visitors to either arrive early or show up late in the day, to use public buses and to follow other tips to improve the traffic flow.
"Anything we can do to change visitor behavior," Gediman said. "The whole theory behind it is if they know the conditions in the park before they get there, they're going to have a better visit."