Gila National Forest
The Gila, as it's called, covers 3.3 million acres—that's 65 mi by 100 mi—and was the first land in the nation to be set aside as a protected "wilderness" by the U.S. Forest Service back in 1924. The area is vast and continues to feel like a great, relatively undiscovered treasure. You are unlikely to come across any crowds, even in peak summer months. Whether you're backpacking or doing day hikes, you have 1,500 mi of incredibly diverse trails to explore. Open camping is permitted throughout the forest, although there are 18 developed campgrounds (all with toilets and seven with potable water). The Gila is an outdoors-lover's paradise: with seemingly endless trails to explore on mountain bikes, white-water rafting (the season usually starts in April), and fishing in rivers, lakes (three of them), and streams. Thirty percent of the forest is closed to vehicular traffic entirely, but the rest is open for touring.
