BALTIMORE, MD - MAY 25:  A general view during the third inning of the Baltimore Orioles and Houston Astros game at Oriole Park at Camden Yards on May 25, 2015 in Baltimore, Maryland.  (Photo by Rob Carr/Getty Images)

The Camden Yards effect: A close look at 25 years of new ballparks

The past 25 years have been a boom period for new baseball venues. Starting with Oriole Park at Camden Yards in 1992, major league teams have opened 21 new ballparks, with another joining the list this season, when the Atlanta Braves start playing at SunTrust Park.