So, now that it's official and the season is over we can say that the Philadelphia Phillies have joined an exclusive club - one of only six franchises to ever have a team finish in first place four seasons in a row. Three pennants in a row has been mentioned repeatedly since last fall, and the fact that no NL club has done it since 1944 certainly lends it an aura of greatness that coming in first four times in a row doesn't carry. But going back to the beginning of the 20th century we find that winning three or more consecutive pennants (AL or NL) has been done 19 times. The maximum is five (New York Yankees 1949-1953 & 1960-1964), and the Yankees have done it nearly half of the times it has been done (9 of 19). In addition to the Pittsburgh Pirates 1901-1903 run, which included only one World Series, there were two clubs that won three straight pennants but no world championships: the Detroit Tigers, 1907-1909, and the New York Giants, 1911-1913. Call them the Buffalo Bills of their day.
How about winning four straight titles of any sort, league or division?
Before the leagues divided into divisions starting in 1969, it had been done only five times - four times by the New York Yankees (the two above plus 1936-1939 & 1955-1958) and once by the New York Giants (1921-1924). Since the leagues broke into divisions in 1969, only five teams have won four or more consecutive division titles. They are: the Oakland A’s (1971-1975, 5 straight); the Cleveland Indians (1995-1999, 5 straight); the Atlanta Braves (1995-2005, 11 straight); the New York Yankees (1998-2006, 9 straight); and the Philadelphia Phillies (2007-2010, 4 straight).
Additional notes on four straight: the Phillies are the sixth franchise to ever finish first four straight years. The Yankees have done it five times. The Braves have done it the longest - eleven (1995-2005). Or fourteen if you count the three years they won the NL West from 1991-1993 as part of a continuous streak, skipping 1994 as an incomplete season. The New York Giants did it first - from 1921-1924. The Oakland A's are the only post-1969 team to not lose a World Series during a run of four straight playoff appearances. The Cleveland Indians finished first five years in a row but did not win the World Series during that period (they reached the Series twice). In the other 105 years as a franchise since 1901, they have finished first five times.
Four straight titles would appear to be a greater accomplishment than three straight pennants in the overall scheme of things: 10 times versus 19 times. But that is mostly based on the fact that before 1969 one outcome required the other. You couldn't get to four straight titles without winning three straight pennants. Since 1969 the record is much closer. Five teams (so far) have made it to the World Series three times or more in row: the Baltimore Orioles, 1969-1971; the Oakland A's, 1972-1974; the New York Yankees, 1976-1978; the A's again from 1988-1990; and the Yankees again from 1998-2001. In comparison, five teams including this year's Phillies have finished first four or more years consecutively; two did it for nine or more years. And four of those teams were since the advent of the three-division/wild card format. Both achievements are rare, but the way things are set up now playing in the World Series three years in a row will become less frequent than winning four titles in a row.