instance_of western league 
The American ___MASK35___ of Professional Baseball Clubs , or simply the American ___MASK35___ ( AL ), is one of two leagues that make up Major ___MASK35___ Baseball ( MLB ) in the United States and Canada . It developed from the Western ___MASK35___ , a minor ___MASK35___ based in the Great Lakes states , which eventually aspired to major ___MASK35___ status . It is sometimes called the Junior Circuit because it claimed Major ___MASK35___ status for the 1901 ___MASK10___ , 25 years after the formation of the National ___MASK35___ ( the " Senior Circuit "). The National ___MASK35___ of Professional Baseball Clubs , known simply as the National ___MASK35___ ( NL ), is the older of two leagues constituting Major ___MASK35___ Baseball ( MLB ) in the United States and Canada , and the world ' s oldest current professional team ___MASK2___ . Founded on February 2 , 1876 , to replace the National Association of Professional Base Ball Players , it is sometimes called the Senior Circuit , in contrast to MLB ' s other league , the American ___MASK35___ , which was founded 25 years later . Both leagues currently have 15 teams . The two league champions of 1903 arranged to compete against each other in the inaugural World Series . After the 1904 champions failed to reach a similar agreement , the two leagues formalized the World Series as an arrangement between the leagues . National ___MASK35___ teams have won 48 of the 112 World Series contested from 1903 to 2016 . The 2016 National ___MASK35___ champions are the Chicago Cubs . At the end of each Major ___MASK35___ Baseball ___MASK10___ , the league leaders of various statistical categories are announced . Leading the league in a particular category is referred to as a " title ". The Western ___MASK35___ is a name given to several circuits in American minor ___MASK35___ baseball . Its earliest progenitor , which existed from 1885 to 1899 , was the predecessor of the American ___MASK35___ . During the 20th century , there were four incarnations of the Western ___MASK35___ , including a Class D loop that played from 1939 -- 41 and an independent loop ( outside of `` organized baseball '' ) that began play in 1995 . This article , however , concentrates on the two Class A leagues that played from 1900 -- 37 and from 1947 -- 58 . The minor leagues went unclassified through 1901 . From 1902 until 1911 , Class A was the highest level in the minor leagues . In 1912 , a new top tier , Class AA , was created ; in 1936 , a second tier , Class A1 , came into being . In 1946 , the Class AA leagues were renamed AAA , and the A1 loops were renamed AA . Thus the Western ___MASK35___ -- whose clubs were actually located in the Great Plains , Rocky Mountain States , the Upper Midwest and the Upper Southwest -- was a top - level minor ___MASK35___ until 1911 , then two levels below Major ___MASK35___ Baseball through 1935 , and three steps removed in 1936 -- 37 and when it was revived in 1947 during the post - war minor ___MASK35___ baseball boom . Its longest - serving franchise was located in Des Moines , Iowa , which joined the WL in 1900 and played continuously through 1937 , when the ___MASK35___ shut down during the Great Depression . Des Moines then rejoined the reborn Western circuit when Colorado Senator Edwin C . Johnson founded it in 1947 ; this team , a Chicago Cubs affiliate called the Des Moines Bruins , then played for the final 12 years of the ___MASK35___ ' s existence .