I don't believe it. I'm in an office at 7 and 53rd, and looking at a live webcam on 8th & 34th (there don't seem to be any 7th Ave. webcams, unfortunately). If there were 250,000 people marching up 7th between 14th and 34th , I'd being seeing/hearing some signs, cause there's no way 250,000 people wouldn't be overflowing that route. I haven't even heard a single siren all day!
I see it is hot and humid in NYC. People marching, yelling and keeping hydrated with water. Don't see any porta-johns. Where for crying out loud do they go pee?