From BR Bullpen
Like most geographically-named leagues, there have been multiple "Northern Leagues" in baseball history. Since the beginning of the Twentieth Century, four leagues have shared the name.
The first Northern League was a class D league centered in the Dakotas and Canada and was in operation from 1902 to 1906. In 1904 the season was shortened on August 8. The league merged with Copper Country Soo League on May 25, 1906 to form the class C Northern-Copper Country League. This league lasted 2 years before folding.
Another Northern League lasted from 1913 to 1917. The league consisted of teams formerly of the Central International League and was a class C league from 1913-1916 and was demoted to Class D in 1917. The league ceased operations on July 4 due to World War I.
The longest-lasting Northern League ran from 1933 to 1971 with a break during World War II. One of the few leagues started during the Depression, former major-leaguer Bruno Haas was the key individual in organizing the new circuit. Cities like Duluth and Winnipeg, members of the original Northern League, were long-standing members of this edition. The league was one of the few to die off in the 1970s after surviving the attrition-heavy 1950s. Perhaps the most famous player in Northern League history was Hank Aaron, who was the league's rookie of the year in 1952. Other notable players included Hall of Famers Orlando Cepeda, Lou Brock, and Jim Palmer.
 Modern Northern League (1993-2010)
The most recent incarnation was created in 1993 through the efforts of new commissioner Miles Wolff. Wolff started the league after many midwestern cities contacted him (through his affiliation with Baseball America) asking how they could get a minor league team. After visiting some of them, most notably Wade Stadium in Duluth, he started contacting potential owners to start the league.
The league started in 1993 with 6 teams: Duluth-Superior Dukes (Duluth, Superior WI), Rochester Aces (Rochester, Minnesota), St. Paul Saints (St. Paul, Minnesota), Sioux Falls Canaries (Sioux Falls, South Dakota), Sioux City Explorers (Sioux City, Iowa) and Thunder Bay Whiskey Jacks (Thunder Bay, Ontario). The prospects for the league were originally "cloudy." Many forecasted an early demise, especially in St. Paul, where competition with the Minnesota Twins led many local sportswriters to consider it a "beer league."
In fact the league was, overall, quite a success with only one franchise, Rochester, failing to attract significant crowds. The ailing Aces franchise was sold to an owner in Winnipeg, Manitoba (Sam Katz) and renamed the Winnipeg Goldeyes.
Part of the success of the league may be the structure of the teams with both salary caps and roster rules. Teams were permitted no more than 4 veterans (5+ years professional experience) and required to have at least as many rookies. The rest of the rosters were made up of players with various years of experience (listed as LS-1 to LS-5 for "limited service).
The league expanded from six to eight teams with the addition of franchises of the Fargo-Moorhead RedHawks (Fargo, North Dakota) and Madison Black Wolf (Madison, Wisconsin). After the 1998 season, the Whiskey Jacks, originally with the second best attendance in the league, was sold and became the Schaumburg Flyers (Schaumburg, Illinois) in 1999.
In 1999, its eight teams merged with the Northeast League, which had begun in 1995. During these years the original Northern League franchises made up the Northern League Central and the Northeast League teams became the Northern League East. Despite becoming one league, the 2 divisions only played each other during the league championship series. In 2002, expansion in the Central added the Joliet JackHammers (Joliet, Illinois) and Gary SouthShore RailCats (Gary, Indiana).
When the four-year agreement ended at the conclusion of the 2002 season, the relationship between the two leagues was ended. The Northeast League was re-established as a separate league (which later reformed as the Canadian-American Association). It was the final year that Miles Wolff remained associated with his creation. Mike Stone replaced him as league commissioner, while Wolff moved East.
During this same period two more teams struggling with attendance and difficult stadiums relocated. In 2001, the Madison Black Wolf became the Lincoln Saltdogs (Lincoln, Nebraska) while in 2003 the Duluth-Superior Dukes became the Kansas City T-Bones (Kansas City, Kansas).
After the 2005 season, the St. Paul Saints, Sioux Falls Canaries, Lincoln Saltdogs and Sioux City Explorers left the Northern League to establish their own independent minor league, called the American Association. The Northern League played the 2006 season as a two-division, eight-team league. After the 2007 season, the two teams from Alberta, Calgary and Edmonton, announced that they were leaving the league. They joined the Golden Baseball League, which was somewhat closer geographically.
Over its 18 seasons, over two dozen players were signed from the Northern League to play in major league baseball. These include players such as J. D. Drew, Kevin Millar, Jeff Zimmerman and Rey Ordoñez. Several former MLB players have played in the league including Dennis "Oil Can" Boyd, Darryl Strawberry, Jack Morris, Pedro Guerrero, and Leon "Bull" Durham. Former MLB players and coaches have also coached or managed in the Northern League including Terry Bevington, Hal Lanier, Wayne Terwilliger, Matt Nokes, and "Dirty" Al Gallagher.
Following the 2010 season the league officially merged with the United Baseball League and Golden Baseball League to create the North American League. Only one team would join the North American League in its first season though, the Lake County Fielders. Schaumburg and Rockford were proposed but faced stadium issues and were not able to join the league; Schaumburg went on hiatus for a year, while Rockford returned to the Frontier League, accompanied by Joliet. Four other teams (Fargo-Moorehead, Gary, Kansas City, and Winnipeg) left to join the American Association
 League structure
The Northern League played a 96-game split season schedule from late May until early September. The division winners in each half qualified for the post-season, though if a team won both halves, the team with the best overall record, regardless of division, qualified as a wild card. Both the league semi-finals and Championship Series were best of five.
During the season, rosters were limited to 22 players, broken into seven classes based on a players years of service. One year of service was defined as one National Association (affiliated) season, or two independent league seasons.
- Rookie: A player with less than one year service. Each team must carry a minimum of five Rookies.
- LS-1: "Limited Service", a player with less than two years.
- LS-2: A player with less than three years.
- LS-3: A player with less than four years.
- LS-4: A player with less than five years. Only four players may be LS-4's.
- LS-5: A player with less than six years.
- Veteran: A player with six or more years. A maximum of four players may be veterans.
- 1993 St. Paul Saints
- 1994 Winnipeg Goldeyes
- 1995 St. Paul Saints
- 1996 St. Paul Saints
- 1997 Duluth-Superior Dukes
- 1998 Fargo-Moorhead Redhawks
- 1999 Albany-Colonie Diamond Dogs
- 2000 Adirondack Lumberjacks
- 2001 New Jersey Jackals
- 2002 New Jersey Jackals
- 2003 Fargo-Moorhead Redhawks
- 2004 St. Paul Saints
- 2005 Gary SouthShore RailCats
- 2006 Fargo-Moorhead Redhawks
- 2007 Gary SouthShore RailCats
- 2008 Kansas City T-Bones
- 2009 Fargo-Moorhead Redhawks
- 2010 Fargo-Moorhead Redhawks
 Cities Represented
- Cavalier, ND: Cavalier 1902
- Crookston, MN: Crookston Crooks 1902-1905
- Devil's Lake, ND: Devil's Lake 1902
- Duluth, MN: Duluth White Sox 1903-1905, moved to Northern-Copper Country League 1906
- Fargo, ND: Fargo 1902-1905, moved to Northern-Copper Country League 1906
- Grand Forks, ND: Grand Forks Forkers 1902-1905, moved to Northern-Copper Country League 1906
- St. Cloud, MN & Brainerd, MN: St. Cloud-Brainerd 1905
- Superior, WI: Superior Longshoremen 1903-1905
- Winnipeg, MB: Winnipeg Maroons 1902-1905, moved to Northern-Copper Country League 1906
- Brandon, MB: Brandon Angels 1908
- Duluth, MN: Duluth White Sox 1908
- Fargo, ND: Fargo Browns 1908
- Winnipeg, MB: Winnipeg Maroons 1908
- Duluth, MN: Duluth White Sox 1913-1916
- Fargo, ND & Moorhead, MN: Fargo-Moorhead Graingrowers 1914-1917
- Fort William, ON: Fort William Canadians 1914-1915
- Fort William, ON & Port Arthur, ON: Fort William-Port Arthur Canadians 1916
- Grand Forks, ND: Grand Forks Flickertails 1913-1915
- The team withdrew from the league on July 5, 1915.
- LaCrosse, WI: LaCrosse Colts 1913
- Minneapolis, MN: Minneapolis Millers 1913
- Minot, ND: Minot Why Nots 1917
- St. Boniface, MB: St. Boniface Bonnies 1915
- St. Paul, MN: St. Paul 1913
- Superior, WI: Superior Red Sox 1913-1915
- Virginia, MN: Virginia Ore Diggers 1913-1916
- Warren, MN: Warren Wanderers 1917
- Winnipeg, MB: Winnipeg Maroons 1913-1917
- Winona, MN: Winona Pirates 1913-1914
- Aberdeen, SD: Aberdeen Pheasants 1946-1971
- Bismarck, ND & Mandan, ND: Bismarck-Mandan Pards 1962-64; Bismarck-Mandan Pards 1966
- Brainerd, MN & Little Falls, MN: Brainerd Muskies 1933; Brainerd-Little Falls Muskies 1934; Brainerd Blues 1935
- Brandon, MB: Brandon Grays 1933
- Crookston, MN: Crookston Pirates 1933-1941
- Duluth, MN: Duluth White Sox 1934 Duluth Dukes 1935-1942, 1946-1955
- Duluth, MN & Superior, WI: Duluth-Superior White Sox 1956-1959; Duluth-Superior Dukes 1960-1970
- East Grand Forks, MN: East Grand Forks Colts 1933
- Eau Claire, WI: Eau Claire Cardinals 1933; Eau Claire Bears 1934-1942, 1946-1953; Eau Claire Braves 1954-1962
- Fargo, ND & Moorhead, MN: Fargo-Moorhead Twins 1933-1942, 1946-1960
- Grand Forks, ND: Grand Forks Chiefs 1934-35; Grand Forks Chiefs 1938-1942, 1946-1963; Grand Forks Dodgers 1964
- Huron, SD: Huron Phillies 1965-1968; Huron Cubs 1969-1970
- Jamestown, ND: Jamestown Jimmies 1936-1937
- Mankato, MN: Mankato Mets 1967-1968
- Minot, ND: Minot Mallards 1958-1960; Minot Mallards 1962
- St. Cloud, MN: St. Cloud Rox 1946-1971
- Sioux Falls, SD: Sioux Falls Canaries 1942, 1946-1953, moved from Nebraska State League 1933-1938; Sioux Falls Packers 1966-1971
- Superior, WI: Superior Blues 1933-1942, 1946-1955
- Watertown, SD: Watertown Expos 1970-1971
- Wausau, WI: Wausau Lumberjacks 1936-1939; Wausau Timberjacks 1940-1942; Wausau Lumberjacks 1956-1957
- Winnipeg, MB: Winnipeg Maroons 1933-1942; Winnipeg Goldeyes 1954-1964; Winnipeg Goldeyes 1969
- Calgary, AB: Calgary Vipers 2005-2007, moved to Golden Baseball League
- Duluth, MN & Superior, WI: Duluth-Superior Dukes 1993-2002, moved to Kansas City, KS
- Edmonton, AB: Edmonton Cracker-Cats 2005-2007, moved to Golden Baseball League
- Fargo, ND & Moorhead, MN: Fargo-Moorhead RedHawks 1996-2010, moved to American Association
- Gary, IN: Gary SouthShore RailCats 2002-2010, moved to American Association
- Joliet, IL: Joliet JackHammers 2002-2010, moved to Frontier League
- Kansas City, KS: Kansas City T-Bones 2003-2010, moved from Duluth, MN & Superior, WI, moved to American Association
- Lincoln, NE: Lincoln Saltdogs 2001-2005, moved from Madison, WI, moved to American Association
- Madison, WI: Madison Black Wolf 1996-2000, moved to Lincoln, NE
- Rochester, MN: Rochester Aces 1993, moved to Winnipeg, MB
- Rockford, IL: Rockford RiverHawks 2010, moved from Frontier League, moved to Frontier League
- St. Paul, MN: St. Paul Saints 1993-2005, moved to American Association
- Schaumburg, IL: Schaumburg Flyers 1999-2010, moved from Thunder Bay, ON
- Sioux City, IA: Sioux City Explorers 1993-2005, moved to American Association
- Sioux Falls, SD: Sioux Falls Canaries 1993-2005, moved to American Association
- Thunder Bay, ON: Thunder Bay Whiskey Jacks 1993-1998, moved to Schaumburg, IL
- Winnipeg, MB: Winnipeg Goldeyes 1994-2010, moved from Rochester, MN, moved to American Association
- Zion, IL: Lake County Fielders 2010, moved to North American League
Members of Northern League East (1999-2002)
- Albany, NY & Colonie, NY: Albany-Colonie Diamond Dogs 1999-2002, moved from Northeast League
- Allentown, PA: Allentown Ambassadors 1999-2002, moved from Northeast League, moved to Northeast League
- Brockton, MA: Brockton Rox 2002, moved to Northeast League
- Elmira, NY: Elmira Pioneers 1999-2002, moved from Northeast League, moved to Northeast League
- Glens Falls, NY: Adirondack Lumberjacks 1999-2002, moved from Northeast League, moved to Northeast League as Bangor Lumberjacks
- Lynn, MA: Massachusetts Mad Dogs 1999, moved from Northeast League
- Montclair, NJ: New Jersey Jackals 1999-2002, moved from Northeast League, moved to Northeast League
- Mountaindale, NY: Catskill Cougars 2000
- Pittsfield, MA: Berkshire Black Bears 2002, moved to Northeast League
- Quebec, QC: les Capitales de Québec 1999-2002, moved to Northeast League
- Waterbury, CT: Waterbury Spirit 1999-2000
 Hall of Fame Alumni
- Hank Aaron, 1952 Eau Claire Bears
- Lou Brock, 1961 St. Cloud Rox
- Steve Carlton, 1964 Winnipeg Goldeyes
- Orlando Cepeda, 1956 St. Cloud Rox
- Jim Palmer, 1964 Aberdeen Pheasants
- Gaylord Perry, 1958 St. Cloud Rox
- Willie Stargell, 1960 Grand Forks Chiefs
- Rube Waddell, 1913 Virginia Ore Diggers