We celebrate the Society for American Baseball Research's fiftieth anniversary with a look back at one of the most pivotal events in major league baseball history - and featured in the group's newly-released commemorative anthology "SABR: 50 at 50".   Longtime Society contributor Bob Bailey ("Four Teams Out: The National League Reduction of 1900") revisits his 1990 Baseball Research Journal article describing how a fledgling 12-team, 1890s-era National League pro baseball monopoly found itself on the brink of implosion - as financial imbalance, competitive disparity, self-dealing common ownership, and a pronounced national economic Depression collectively threatened the circuit's very survival by decade's end.   As a result, the NL eliminated four franchises for the 1900 season - all former refugees from the previous American Association:

• Ned Hanlon's "small ball"-centric (original) Baltimore Orioles (AA: 1882-92; NL: 1893-99);
• The Cy Young-led Cleveland Spiders (AA: 1887-88; NL: 1889-99);
• The woeful original Washington Senators (AA: 1891 as the "Statesmen"; NL: 1892-99); AND
• Louisville's first and only major league baseball team - the Colonels (née Eclipse)

By 1901, Baltimore, Cleveland and Washington each had new franchises in Ban Johnson's NL-challenging American League - with Louisville never returning to major league play.