Also, you may want to purchase a copy of Coleman's Guide to National Forest Campgrounds. It will have nearly 4000 campgrounds listed and most are low cost or free and most will not have hookups. You can start here:
http://www.forestcamping.com/dow/list/nflist.htm, but you will also find the Coleman's Guide indespensible if not hard to read.
This will also help:
http://www.fs.fed.us/recreation/map/finder.shtml