By Laura S. Bly, USA Today

Contrary to the assumption that cash-strapped tourists flock to U.S. national parks during a recession, a University of Georgia study ties a decline of nearly 10 million visitors since 1998 to a lousy economy.

Though overall park visitation has dropped to about 280 million, the decrease hasn’t been uniform, note researchers at UGA’s Warnell School of Forestry and Natural Resources and the Catholic University of Korea’s department of economics.

For example, visits to Yellowstone and Yosemite were up sharply between 2000 and 2011. But the Great Smoky Mountains National Park, the United States’ most visited, saw a 7 percent decrease in visitation over the same time period.

The increases for Yosemite and Yellowstone could be credited to their “high international recognition,” said Michael Tarrant, a Warnell School professor and director of the study abroad program Global Programs in Sustainability.

And even as visitation at such iconic parks is up, time spent per visit has declined nearly 15 percent systemwide over the past two decades, a USA Today story noted this summer.

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 Wyoming’s Grand Teton, the hours the average visitor spent in the park dipped from 10 to about 6½ over the past two decades. At Grand Canyon, hours spent were down 10 percent, and at Cape Hatteras, N.C., that figure had dropped more than 19 percent.

“Visitation to some national parks may be incidental to tourism,” Tarrant said in a release. “For example, U.S. Highway 441 is the only main road in the Smokies and receives substantial non-tourism and thoroughfare traffic. Consequently, reduced visitation to such parks may be a function of lower vehicle miles traveled in the past decade. National transportation statistics show that traffic on U.S. 441 has had a reduction from 3.03 trillion in 2007 to 2.96 trillion miles in 2011.”

The UGA study suggests that when faced with tighter budgets, consumers will cut out non-essential goods and services and visit local city or neighborhood parks rather than drive to national parks. Another potential factor: while national parks are a bargain compared to theme parks, “they don’t offer the same kind of recreation experience,” the study says.

Some researchers speculated that when money is tight, people would turn to national parks for cheaper recreation options. But that does not seem to be happening, or the substitution is perhaps limited to national parks of national and international reputation, the study said.