Speed’s John Dagsy is reporting that the American Le Mans Series and the GRAND-AM Rolex Sports Car Series are expected to announce tomorrow that they are merging from 2014. ALMS and GRAND AM are the top two sports car racing series in the U.S. but have vastly different philosophies. GRAND AM is controlled by the France family — which is to say NASCAR — runs spec cars to control costs. ALMS has a tie in the 24 Hours of Le Mans and runs a much more open rulebook. ALMS cars are also quicker than GRAND AM cars.

Having one series could be good American road racing. Or not, depending upon the rules the combined series adopt. But in any case, this is a major game changer for racing in the U.S. More details as they become available.