Check my reply to your sibling comment for some links. The only place I know of where it's specifically illegal is US national parks (only national parks — you

Check my reply to your sibling comment for some links. The only place I know of where it's specifically illegal is US national parks (only national parks — you're fine in Bureau of Land Management and Forest Service territories). Of course, if you have to trespass to make the jump, that's itself illegal, but that has nothing to do with BASE jumping.