I suspect its power lines since when I drive around listening to AM radio there are certain spots in my neighborhood that completely wipe out the signal with noise
It *may* be power lines but it could also be customer equipment coupling crap onto the power lines. If it's strong enough to wipe out a broadcast receiver then it should definitely get someone's attention though. The local utility here has an engineering department and they're who I've contacted for RFI resolution. If you're inclined to try and track it down to the nearest structure or pole, any help you give them will be to your benefit.