Unicoi State Park, GA
One of Georgia’s most popular parks, 1,050-acre Unicoi State Park beckons people out of the city, as it's just 90 miles north of Atlanta. During the state’s 1830s Gold Rush, the area played a significant role in mining and shipping the metal to market. These days, however, visitors strike gold by way of 12 miles of hiking trails, eight miles of singletrack, and a 53-acre swimming and canoeing lake.

Mount Baker-Snoqualmie National Forest, WA
Washington’s Mount Baker-Snoqualmie National Forest is no easy walk in the park. Glacier-covered peaks reaching up more than 10,000 feet plunge quickly into valleys at sea level. Huge masses of rain clouds plague the mountain range most of the year, while valley bottoms are typically dry. Twenty-foot snowfalls dump in winter (hence why you should explore this park at the end of summer). And did we mention the active volcano? Then again, if the park's environs weren’t this tough, you just wouldn’t be satisfied.

Big Bend National Park, TX
Texas’ Big Bend National Park, one of the largest and least visited national parks in the country, administers a 196-mile portion of the Rio Grande Wild and Scenic River. Demarking the border with Mexico, all U.S. roads end at the Rio Grande, which abruptly changes its course along the park’s southern boundary to form the distinct curve that gives the park its name. Because of this park's relative anonymity, it'll be crowd-free most of the year. But September can bring a slight reprieve from summer's heat.

Baxter State Park, ME
Baxter, a 202,000-acre park known for its abundance of wildlife and wilderness, is a popular spot for outdoor adventurers. Activities include canoeing, kayaking, hiking, camping, fishing, climbing, and more. It also hosts 5,268-foot Mount Katahdin, the state's tallest peak and the last stop on the Appalachian Trail. Fall color usually peaks here in late September, so get out there and enjoy it.

Hovenweep National Monument, CO & UT
Hovenweep National Monument protects six units of prehistoric villages that represent the cultural climax of Pueblo farming villages more than 700 years ago. Tumbled piles of masonry, small cliff dwellings and towers, and the quantities of refuse scattered over the canyon slopes leave little doubt that a sizable population once lived in this now desolate country. Fall brings relief from scorching summer days, and it's the best time to enjoy short hikes, natural quiet, and some of the finest examples of ancestral Puebloan architecture in the southwest. The trail system provides access to each of the cultural site units.

Apostle Islands National Lakeshore, WI
Wisconsin's northernmost tip breaks into 21 islands in the cobalt-blue waters of Lake Superior. French missionaries, who spied the archipelago from a distance, counted 12 islands and thus named them the Apostles. These days, sea kayaking between islands is immensely popular. Old-growth forests, historic lighthouses, cavernous sea caves, and red sandstone bluffs create an unforgettable landscape. And Stockton Island has one of the greatest concentrations of black bears in North America. Sea kayakers are advised to wear wet or dry suits; conditions can change rapidly on the lake even on mild fall days.

Craters of the Moon National Monument, ID
Temperatures cool down during this period, and the lack of wind can make this some of the most ideal weather during the entire year. Ranger-led programs are no longer presented, but the crowds are gone as well, making it an ideal time to see the monument on your own. Backpack into the wilderness area; camp sites are easy to find, and Aspen trees in the mountains north of the monument will be in full autumn dress.

Glen Canyon National Recreation Area, AZ & UT
Encompassing more than 1.2 million acres, Glen Canyon National Recreation Area offers unparalleled water-based and backcountry opportunities. Kayaking, hiking, and mountain biking are popular active pursuits, while boating, fishing, and scenic driving are for the more laid-back crowd. The recreation area stretches for hundreds of miles from Lees Ferry in Arizona to the Orange Cliffs of southern Utah, encompassing scenic vistas, geologic wonders, and a panorama of human history.

Adirondack Mountains, NY
September in New York’s Adirondack Mountains highlights the emergence of fall in the beautiful backcountry, so what better way to enjoy it than sky-high in a hot-air balloon? Each September, the Adirondack Balloon Festival organizes hundreds of ballooners in the Lake George area. Hop aboard and float silently over the autumnal horizon.

Delaware Water Gap National Recreation Area, PA & NJ
Escape the city heat and canoe the Gap, the awe-inspiring hole in the Appalachians through which the Delaware River flows. This craggy, spectacular gap, on the border of northwestern New Jersey and northeastern Pennsylvania, is more than a mile wide. Yet the National Recreation Area that surrounds the gap offers much more than a break in the rock, incluidng 40 miles of the middle Delaware River and almost 70,000 acres of land along its shores. Hiking, biking, and climbing are the favorite alternatives to canoeing and fishing.