Rocketville is (was) next to the (remains of) the Grand Dam, a dam on the Raccoon River, which flows directly into the MSMG river about 12 miles north of Aaaa. Since Aaaa isn't right up on the river, it won't get flooded as much
LIVE AERIAL VIEW OF ROCKETVILLE SHORTLY AFTER DAM BREACH; MOST HOMES CLOSER TO THE DAM HAVE BEEN SIMPLY TORN APART. ROCKETVILLE, BEING A TOWN OF NEARLY 4500, IS EXPECTED TO HAVE A MAXIMUM OF ONLY 975 SURVIVORS.