National Parks Pass – a mere $80 provides access for a year to spectacular sites and historical treasures for the entire family for a year. You will find a free guide to all 388 National Parks and more information at Nationalparks.org
Free Annual Pass for U.S. Military
Jr. Rangers – While visiting your National or State Park ask about their Jr. Ranger programs. Which are free educational activities lead by rangers and staff (there may be a small supply fee or donation request). Your child may be given a booklet or page of questions to answer or your family may join a ranger on a hike or participate in a craft activity. No matter what the whole family will gain from the engaging experience and the kids will earn a souvenir badge or patch.
Jr .Rangers are highly recommended by a kid on the road
Science Centers and Zoos make great educational stops along the way. For the best deal get a membership with a museum that is part of ASTC. Then you will get free or reduced rates at reciprocal museums across the country. Zoos should be a part of the Association of Zoos & Aquariums (AZA).
There are three locations (that we know of) that offer memberships to both Science Centers and Zoos. Most others offer only one or the other. Both of these sites have a downloadable membership that you can mail in. Compare reciprocation lists to see which one serves your needs the best.