They are letting people park here tonight,I'm going to assume they're going to let you stay in until the fireworks are done by 11-11:30
Generally the park closes at dark. But as long as the grass isn't too wet they will allow parking until the fireworks are over.
I'm out of town right now so I'm not sure they normally don't let people park at the park so if they are letting you I would assume it will be until the fireworks are over
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