SABR was founded in 1971 in Cooperstown, NY. From the SABR website:
The Society for American Baseball Research (SABR) was established in Cooperstown, New York in August, 1971. Our mission is to foster the study of baseball past and present, and to provide an outlet for educational, historical and research information about the game.
Today, there are over 7,000 members around the globe, dozens of local chapters, and many committees dedicated to specific aspects of baseball past, present, and future.
For more information, visit the SABR website.