I don't know about the USA rulebook, but I ride under British Cycling's rules. I don't think they'd be that different? And it is pretty simple to understand (I've read the MTB, road and track sections - not bothering with BMX as I don't race them). Once you give it a good read, you probably won't need to read it again and it avoids turning up for a race and not being able to race because your equipment doesn't check out.