120,000 reserved seats were sold out before I got to work so if you planned to go and don't have tickets yet, well, you're fucked. Belmont Park is open for something like nine or ten months out of the year, I think. (I don't follow the ponies like my mom did and if you really want to know, Google it.) It's a beautiful park and it's a nice outing for a day. Just not tomorrow. You can picnic and take a tour through the stables (best to do that on a cool, breezy day, trust me), and have a nice time. If you have business anywhere near the park tomorrow, unrelated to the race, well, it sucks to be you. Traffic's gonna be insane around there. Good luck!
Update: I stuck the link in there anyway, cause that's the kinda guy I am.