When the DNC had their convention in New York in 1992, it did cause a dip in ticket sales. Part of the problem is that a lot of New Yorkers flee the city during these conventions and the thousands of conventioneers who come into town simply don't have the time to see a lot of shows. The delegates, party officials, journalists etc... will be cooped up in Madison Square Garden listening to speeches and having meetings everyday from roughly noon until 11pm so they're not out seeing shows and spending money. Add to that the fact that a lot of potential tourists will avoid New York that week fearing traffic jams, protest marches, security headaches and the threat of terrorist action.
Because of all of that, I would bet that just about every show is going to see at least a small drop in ticket sales for the week with the shows that are already struggling taking a really significant hit.
"What a story........ everything but the bloodhounds snappin' at her rear end." -- Birdie
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"The Devil Be Hittin' Me" -- Whitney