they only won because the damn Brits and French gave them recognition after the battle, and interfered with their fleets. There was a lot of hatred in the US for those European meddlers after that. Hmm... immediate consequences... I suppose it would have been a severe blow to the Confederacy, what with Lee being beaten and Vicksburg falling damn near simultaneously. Hard to say if the CSA could ever have rebounded after that.
Long term consequences.... I suppose the reunited US might have gone on to be a real world class power, instead of becoming such an insular place as it is today. Sure, we have real global economic power, but politically and diplomatically, we're a backwater. The US might even have gotten involved in some of the great wars that spread across Europe, although I hope we would have stayed out of all those colonial wars that happened when all the European empires shredded themselves so violently. The US would certainly never have built the huge fleets it operates on both oceans now; originally, the idea was to become so powerful on the seas that Europe could never interfere with us again, although that turned out to be rather pointless, as Europe simply never bothered with America much after the ACW....