Saturday April 16th was not just officially recognized as "Foursquare Day" by fourteen different cities this year, including the company's home base of New York City, but it also marked the busiest day the service has ever recorded, with more than three million checkins around the world - the first time this number has been achieved. To give an idea to the magnitude of this achievement, in March of 2010, the company announced its biggest day ever was 275,000 checkins, making Saturday's mark more than 1,000% higher.
The number was calculated by Foursquare's Harry Heymann, shared by founder Dennis Crowley on Twitter, and repeated by Siobhan Quinn and other team members.
Foursquare reports it now has more than 8 million registered users, achieving the 8 million mark two months after it reached 7 million in February, 6 million in January and 5 million in December. Loosely tracked, the service is expanding around a million new accounts a month, and the number of checkins on Saturday accounted for roughly a checkin per two and a half registered users. Those active on Saturday (myself included) landed the Foursquare Day 2011 badge, an annual tradition.
After initial skepticism on the service, I bet on it following the hire of Blogger's Siobhan Quinn and other smart folks, including Dolapo Falola, formerly of Google, via Thing Labs and AOL. Now even my wife, not an early adopter, is checking in from place to place, and racking up her unfair share of badges. We both counted among Saturday's statistics.