CNN's SI.com has the story: Oriole Park at Camden Yards hit the 50 million fan attendance mark Tuesday night, August 19th, reaching the milestone quicker than any ballpark in baseball history. Kevin Gracie, a 24-year-old student at the University of Baltimore School of Law, arrived to watch the O's play the Red Sox, unaware that by passing through the gates he was the 50 millionth fan to do so. Gracie won $50,000 plus season tickets for five years.
Another milestone, set to be crossed sometime during the upcoming weekend series against the Yankees, will net a lucky fan $100,000 and season tickets for five years. That milestone will mark 100 million fans since the O's arrived in Baltimore.
