Partying in the intersection of 19th st. and Valencia. Traffic was blocked in all four directions for the entire evening. This was in no way a planned event (that I was aware of), but instead a spontaneous gathering of revelers. I arrived when there were maybe 100 people present, by 1am the number was probably 10 times that, and The Extra Action Marching Band arrived and played. There was also the best amateur fireworks display I have ever seen. Apparently these parties were occurring all over San Francisco, every couple of blocks. The next closest one was at 16th and Valencia, 3 blocks away.