Jon Stewart's Rally for Sanity generated the most check-ins in Foursquare's short history, the company confirmed with me today.

The total number of check-ins topped 25,000. I'm not sure if that number is impressive or not, given that it seemed like every young person in DC was was walking in the direction of the Mall on Saturday. On the other hand, cell phone service was truly abysmal that day, so imagine how many people might have checked in if they'd been able to get their phones to work.