Top 10 national parks by number of recreational visitors in 2004. It surprises me that the Great Smoky Mountains National Park beats the Grand Canyon by twice as many visitors.

• 1. Great Smoky Mountains National Park 9,167,046
• 2. Grand Canyon National Park 4,326,234
• 3. Cuyahoga Valley National Park 3,306,175
• 4. Yosemite National Park 3,280,911
• 5. Olympic National Park 3,073,722
• 6. Yellowstone National Park 2,868,317
• 7. Rocky Mountain National Park 2,781,899
• 8. Zion National Park 2,677,342
• 9. Grand Teton National Park 2,360,373
• 10. Acadia National Park 2,207,847

Source: National Park Service