Most Dog-Friendly National Parks
The National Park Service has pretty strict rules about dogs at most of its national parks, but some of them are dog-friendly. Many of the other natural park units and battlefields the NPS manages are actually very dog friendly. By dog friendly, I mean that dogs are allowed on most hiking trails and in campsites. It goes without saying that dogs have to be on a leash. Dogs that aren't service animals aren't allowed in visitor centers or swimming areas anywhere, as far as I can tell.
I understand why the NPS disallows dogs at a lot of the most popular national parks, because dogs just wouldn't be compatible with all the other uses (for example, a dog might start barking at a mule on Bright Angel trail in the Grand Canyon). Another good reason to not bring your dog is bears – bears and dogs are a really bad combination, and a bear will easily kill a dog.
The Eastern national parks seem to have a more relaxed pet policy than the Western national parks. I think the National Park Service should give more thought to allowing on-leash dogs into some of the other national parks, based on what I've seen at Hot Springs, Acadia, and Shenandoah. The US Forest Service and Bureau of Land Management are not as strict about dogs as the National Park Service. Most state park systems are also very dog friendly, though there are plenty of individual state parks where dogs are restricted, usually because it is an environmentally sensitive area.
I'll give descriptions of some of the more dog-friendly parks below. This certainly isn’t all of them, but I have taken my dog to all of them except Acadia. I've been to Acadia, but without Molson :0. I'm also going to put in links to my EveryPark.com web site. I'm trying to get a lot of dog-friendly travel information for all of the parks (national, state, and local) and organize it on my web site. I'd love to be able to plan a trip somewhere and be able to find out information like – this park has a doggy swimming area, 6 miles of good trails for dogs, an off-leash area, and a dog-friendly campsite.
Hot Springs National Park – this is a very dog-friendly park. Dogs are allowed on all of the trails, and in the campground. There are quite a few miles of trails here, and there is nice shade along the way. There aren't any particular problems with wildlife here – the park is basically spread throughout the small city of Hot Springs.
Shenandoah National Park – Dogs are allowed on most, but not all trails. The most heavily used trails (usually the shortest or the nature trails) are off-limits to dogs. This shouldn't really affect your vacation that much, as the hikes dogs are allowed on are fantastic. The entire Appalachian Trail throughout Shenandoah is open to dogs (unlike Great Smoky Mountains National Park), as are many of its side trails.
Blue Ridge Parkway – All trails open to dogs. This is a fantastic national park unit – basically, 5 times longer than Shenandoah, with more cultural and hiking opportunities, and better views. It is also far better for dogs than Great Smoky Mountains National Park. Not just a highway, it really takes in some of the best hiking in the country.
Acadia National Park – 100 miles of trails open to dogs. The carriage road network is open for dogs. This is about 45 miles of 12 foot wide gravel paths that wind throughout the park. Perfect for taking a walk with your dog. The trails that are not open to dogs are steep and dangerous – for instance, the beehive trail involves climbing up iron ladder rungs on sheer cliff faces, so you would have to carry your dog on your back if they let you bring a pet. Dogs also aren't allowed in the lakes, or on the swimming beaches (except September 15 to May 15). Acadia is an excellent place to bring your dog.
Padre Island National Seashore – Dogs allowed on the beach, except right in front of the visitor center (about a quarter mile of the 70 miles of beach is off-limits, no big deal). No real hiking trails here, but you can certainly walk up and down the beach as far as you want to go.
Russell Cave National Monument – Dogs are allowed on the two trails here. This is a great example of a smaller National Park Service unit with dog-friendly policies. Though the trails are short, you can bring your dog as long as the dog is on a leash. I wouldn't go way out of my way to go to this national monument, because it's just a big rock shelter with a stream coming out of it and an overgrown nature trail that goes up the hill behind it. The drive in from the north is fantastic, but don’t try it in an RV or anything towing a trailer!
I'll be following up this post with more information about dog friendly national parks.