Most Americans are traveling far less than in years past, due to one of the worst economic downturns in decades. Many are looking close to home for a place to spend their summer vacation, and that will likely mean record crowds at state and national parks.

Most people would probably guess that one of the nation's iconic western parks - Yellowstone, Yosemite or Grand Canyon - would be the most crowded. But in fact, a park located in the eastern United States sees as many visitors annually as those three better-known western ones combined.

It's Great Smoky Mountains National Park, which straddles the border between North Carolina and Tennessee. 

(Click to view photo slideshow of the park.)

Park is easy to get to, and people come

Ranger Bob Miller says this park hosts well over 9 million visitors every year, far more than any other national park.

"By comparison, Grand Canyon National Park is second with about 4.5 million. Yosemite and Yellowstone have about 3 million each."

The reason for that, he explains, is the park's location, near the densely populated eastern seaboard.

"A hundred million people could drive here in a day," he adds.

Because it's such a popular destination, the soothing sounds of nature in the Smokies blend with the far-less-soothing sounds of traffic. With so many people trying to find a slice of nature to enjoy, you wonder how a park like Smoky Mountains survives all the attention.

But Miller says it isn't the park that suffers the most, it's the visitors' experience in the park. He points to an area called Cade's Cove.

"[It] is an 11-mile [17-km], one-way loop road through an historic district. Real scenic, lots of wildlife to see - bears and deer and turkey - and it's just a real popular destination. It isn't unusual for you to be stuck in traffic for three hours on that 11-mile loop road."

Worse than the traffic, though, is the impact the region's growing population is having on the park's air quality. The Smokies are named for the blue mist that always seems to hover around the peaks and valleys. But because it sits downwind of some of the nation's most heavily industrialized areas, Miller says the Smokies are far smokier than they should be.

"[There are] ozone levels that are high enough to damage about 30 species of plants in the park. We also have acid deposition that's as acidic as vinegar in some cases, where rain and fog can descend at pH [acidity levels] under four."

In contrast, pure rain has a pH of about six.

Attracting a new generation of park visitors

Still, despite all these people problems, Miller says as Great Smoky Mountains National Park celebrates its 75th year, the Park Service is focused on keeping people coming.

"If you look historically at the last 75 years or so, the average visitor has been a white, middle-class family that grew up with the family camping trip, have fond memories of that and pass it along to their kids. But increasingly, the demographic of America is changing."

This new average citizen is less interested in nature, less interested, in fact, in being outdoors at all.

"You know, kids, instead of being out playing out-of-doors, are spending a lot more time online on Facebook and on all kinds of electronic media. They're not activities that really get you in touch with nature," Miller points out, adding, "And a lot of families don't have the time to spend taking their kids out and getting involved with nature."

So rather than waiting for the visitors to come to the park, the Park Service is taking the park to the visitors. Rangers are presenting nature programs at local schools, and they're also experimenting with online tools, like podcasts and a Virtual Visitors Center.

Natural beauty still the biggest draw

The fact that so many people visit Great Smoky Mountains National Park, in spite of the crowds and the noise and the pollution, is perhaps the best possible testament to the park's enduring beauty. As Ranger Bob Miller points out, it has 200,000 hectares of forest, 1,300 kilometers of walking trails, 1,100 kilometers of fishable streams, and a wealth of plant and animal life few other parks can rival.

"We have about 200 species of birds, a lot of which are neo-tropical. We've also got 60 species of mammals, ranging from lesser shrews, which are the weight of a dime and less than an inch [2 centimeters] long, to 800- or 900-pound [350- or 400-kilo] elk. We have something in the range of 1,600 bears in this park, which is somewhere in the range of two per square mile [one per square km]." There are also 1,600 species of plants, including well over 100 tree varieties.

More than enough reason, park visitors seem to believe, to endure a little traffic to enjoy a whole lot of spectacular natural beauty.