Doing your homework can help you make the most of your trip; it can also help you avoid crowds. For park brochures and general planning information, contact each park directly.

Another good source of information -- and an important nonprofit advocate for America's national parks -- is the National Parks Conservation Association, 777 6th St., NW, Ste. 700, Washington, DC 20001 (tel. 800/628-7275 or 202/223-6722; www.npca.org).

A Word on Nature Associations

Throughout this guide, you'll read that a certain nature association or organization operates a particular park's bookstore. Practically every national park has a bookstore, and some have several. Bookstores are excellent sources for maps, guidebooks, videos, postcards, posters, and the like. Most of the nature associations offer memberships (usually $25-$35 per year for individuals) that entitle the member to discounts of 15% to 20% on all purchases. You'll also usually get a regular newsletter. Some of the larger nature associations also sponsor workshops and field trips, and membership usually gets you a discount for those as well.

For frequent travelers, here's the really good news: Membership in one nature association almost always entitles you to a 15% to 20% discount at other nature association bookstores at national parks, monuments, historic sites, and recreation areas. For those of us who like to collect books, topographical maps, posters, and so on, the savings add up quickly. And we can also feel very smug about what a good deed we're doing in supporting these nonprofit groups.

Visitor Centers

Your first stop at any national park should be the visitor center. Some large parks have more than one, and we list the location of each. Not only will you learn the history of the park, but you'll also get timely information such as road and trail closures, updates on safety issues, and the schedule for ranger programs. Visitor center hours usually vary by season; most are open daily from 8am until 6 or 7pm in summer, closing earlier at other times. Many park visitor centers close for New Year's Day, Thanksgiving, and Christmas, even though the parks themselves, especially those with camping, usually remain open.

Fees & Permits

Though fees have increased in the past few years, visiting a national park is still a bargain -- a steal compared to the prices you'd pay for a theme park or even a movie. Entry fees, ranging from free to $25, are usually charged per private vehicle (for up to 1 week), regardless of how many visitors you stuff inside. Those arriving on foot, motorcycle, or bicycle usually pay lower per-person fees. Some parks offer passes good for unlimited visits to the same park, or a few nearby parks, for 12 months.

National Parks/Federal Land Passes

Those who enjoy vacationing at national parks, national forests, and other federal lands have opportunities to save quite a bit of money by using the federal government's annual passes.

The America the Beautiful -- National Parks and Federal Recreational Lands Pass costs $80 for 1 year, from the date of purchase, for the general public. It provides free admission for the pass holder, and those in his or her vehicle, to recreation sites that charge vehicle entrance fees on lands administered by the National Park Service, U.S. Forest Service, U.S. Fish and Wildlife Service, Bureau of Land Management, and Bureau of Reclamation. At areas that charge per-person fees, the passes are good for the pass holder, plus three additional adults. Children 15 and under are admitted free.

The passes are also available for U.S. citizens and permanent residents ages 62 and older for a lifetime fee of $10 -- the Senior Pass -- and are free for U.S. residents and permanent residents with disabilities -- the Access Pass. The Senior and Access passes also provide 50% discounts on some fees, such as those for camping and ranger-guided tours in some parks, including Carlsbad Caverns.

The Senior and Access passes can be obtained by mail with an application form available online with a $10 processing fee, or without the processing fee in person at national parks, U.S. Forest Service offices, and other federal recreation sites.

The general public version (the $80 one) can be purchased in person, by phone (tel. 888/275-8747, ext. 1), or online at http://store.usgs.gov/pass, a website that also provides complete information about the passes.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.