This ride took place on the eve of the 2004 Republican National Convention. The police, anticipating chaos and perhaps hoping to practice crowd control techniques, notified the press and local cycling organizations that they planned to arrest any participants who broke traffic laws. They had hundreds of police monitoring from the sides of the road, bicycles, scooters, two helicopters, and a blimp. This had the opposite of the intended effect, drawing out thousands of people who probably would not otherwise have attended. The press later estimated turnout at 5000. Something like 250 of these were arrested near the end but I never saw it.
Click on the thumbnails to see the images in larger size