Who doesn't like free parking? I know our travels would not be sustainable without the ability to save entire weeks of camping fees at a time. Of course, free isn't our only criteria for rating a great place. Parking lots are not high on our list of sights to see, and we'll happily drive a dozen extra miles down a two-track to find a free spot in the wilderness. I can't count the number of times that Tricia and I have thanked the BLM for helping protect such beautiful lands for public use.
One of the best ways to do this (especially out West) is through use of public land from the Bureau of Land Management (or BLM in common parlance). As a Michigander, the concept was a little foreign to me, but the agency manages camping and recreation areas in numerous states. They range from full, paid campgrounds with bathrooms and water to empty desert range for the low low cost of free (well, maybe some tax dollars). Freecampsites.net has most of the established camping spots documented already, but there's so much more to choose from!
The only catch is that to make use of this land legally, you need to know where it is. Some BLM land is leased out to entities such as oil conglomerates, who don't like uninvited guests (oil rigs are full of dangerous liabilities). The BLM sells downloads and paper maps, but you have buy copies for each state, which are subdivided into sections that each have their own map. They're not expensive, but if you're a full-timer, they add up. Plus, if you're going to a new area in a different state, it's hard to know where you'll be spending the night if you can't get a map until you find the local BLM office.
Geocommunicator displays locations of all BLM offices nationwide, and I've heard it allows you to view BLM land, but it's a much clunkier map that requires constant internet to refresh. I'd prefer to have it offline, and that's where Google Earth Comes in.
This overlay file* is a compilation of all the BLM public use maps formatted for Google Earth. I found it on a forum and have spent our first year on the road testing it. Just download, double-click, and the file should open with Google Earth.
(If that doesn't work, right-click and "open with" should allow you to open with Google).
Depending on your GPS skills, it's possible to locate spots that are pretty accessible to nearby attractions. Unfortunately, these have a much higher likelihood of being abused, and we've managed to find sites that had more pre-existing trash than we had room to carry out. On the other hand, there are often patches of privately owned land smack dab in the middle of an otherwise free camping area. In New Mexico, we were able to shoe-horn ourselves into a tiny flat patch near a road to get in a much-needed rest day.
But wait, there's more! Another source of many magical nights of boondocking for us has been dispersed camping in National Forests. Locations for these are handily available in Google Earth as well. Just look in the lower left corner for the "Layers" menu. Use the + sign/arrows to expand More > Parks/Recreation Areas > USDA Forest Service.
*This is a personal file for noncommercial use and should be treated as advice only. It is not intended as sole reference for boundaries or navigation. We recommend calling your local BLM office to verify any areas you plan to visit. Please obey all posted signs.