We assume the organizers had no idea of how many people would attend as it soon became apparent the crowds acutely overwhelmed the ability to proceed with original plans. We waited for three hours for the march to pass us (and we were one block from the beginning) in the first row against the barriers, with about 40 people deep behind us. Luckily, the Workmen's Circle provided Klezmer music near us to help pass the time, with some singing old Yiddish union songs mixed in. After seeing no movement, we decided to walk home, guessing it would take all day to get the tens of thousands into the march route. We then saw the streets east of 2nd Avenue were completely filled with people unknowingly waiting to join the procession. There is no way they ever would.Traffic was stopped on Third Ave and Lex for 8 blocks, and we assume in most of midtown. Wonderful to see so many sympathizers, but unfortunate that they probably would not get a chance to march in the procession. We will check TV news tonight to see the scope.