The Thunder Bay Junior A Hockey League (TBJHL) was a Canadian junior ice hockey league that existed from c. 1920 to 1980.  The TBJHL operated in Northwestern Ontario, primarily in the Thunder Bay region.
 The Thunder Bay Junior A Hockey League was what is now known as a Major Junior hockey league from roughly 1920 until the Canadian Amateur Hockey Association realignment of 1970.  After 1970, the TBJHL was relegated to Tier II Junior A and competed for the Manitoba Centennial Trophy until the league folded in 1980.
 Thunder Bay and the TBJHL was considered on the border region of what people would call Eastern Canada and Western Canada.  Due to its location, the Thunder Bay league often switched from East to West year-to-year in National playdowns.  The league's remoteness resulted in keeping the league's few teams from competing in the neighbouring Manitoba Junior Hockey League or Northern Ontario Junior Hockey League, making the league's existence a necessity to the region's hockey community.
 Thunder Bay Junior A Hockey League teams made the Memorial Cup finals four times in fifty years, winning Canada's top junior hockey prize in 1922 (Fort William War Veterans) and 1948 (Port Arthur West End Bruins).
 The TBJHL is the indirect predecessor of the Superior International Junior Hockey League who brought a Junior A league back to the region in 2001, 21 years after the TBJHL folded.
 Although hockey in Thunder Bay dates back well before 1920, the Thunder Bay Junior Hockey League first competed in Memorial Cup action in 1921.  In only their second year of operation at the Junior A level, the league celebrated their first National championship as the Fort William War Veterans defeated the Regina Pats 5-4 and tied them 3–3 to win the championship.  To get there, the Vets had to defeat Toronto Aura Lee in the Eastern Canada final, beating them 5–3 in a one-game showdown.
 It took 26 years for a team from the Thunder Bay Junior A Hockey League to repeat the feat.  In 1947–48, the Port Arthur West End Bruins finished the regular season in first place with a record of 9 wins, no losses, no ties.  They were given a berth directly into the league final where they met the Fort William Columbus Canadiens.  The first game resulted in a 7–7 tie, and the Bruins won the second game 9–7.  Game three sparked some controversy as the game was tied 5-5 and the Columbus Canadiens walked off the ice.  In response, the league ruled the game a forfeit in the Bruins favour.  Games four and five were won by the Bruins 8-3 and 5–3 to give the series and league championship to the Bruins 4-games-to-none with 1 tie.  In the Eastern Canadian semi-final, the Bruins had to play the Manitoba Junior Hockey League's Winnipeg Monarchs.  Port Arthur won game one 12–3, game two 6–4, and game three 10–4.  The Monarchs started to rally, winning game four 7-5 and game five 5–3.  Finally, in game six, the Bruins were able to put the final nail in the coffin as they won 7-2 and took the series 4-games-to-2.  Next, Port Arthur found themselves in the Abbott Cup final against the Southern Alberta Junior Hockey League's Lethbridge Native Sons.  Lethbridge took game one 6-1 and game two 7–6.  Port Arthur came back with a 7–4 win.  Lethbridge put the series on the brink with a 5–4 win before Port Arthur came back with three solid victories; 5–0, 6–4, 11–1; to come from behind and take the Abbott Cup.  This earned them a berth in the Memorial Cup against the Ontario Hockey Association's Barrie Flyers in Toronto.  Ignited by the Abbott Cup final comeback, the Bruins kept on rolling, sweeping the Flyers 4-games-to-none with scores of 10–8, 8–1, 5–4, and 9-8 respectively.  This would be the final Memorial Cup won by a TBJHL team.
 From the 1964 until 1969, the TBJHL had a rivalry and was in direct competition annually for the TBAHA seed to the Memorial Cup against the neighbouring Northwestern Ontario Junior Hockey League.  By 1969, the NWOJHL had dropped to Junior B and may have become the Thunder Bay Junior B Hockey League, the TBJHL's feeder league in the 1970s.
 In 1970, the Thunder Bay Junior A Hockey League was caught in the transformation of Junior hockey.  In the spring of 1970, the Fort William Westfort Hurricanes defeated the Port Arthur Marrs 3-games-to-2 and the Fort William Canadiens 4-games-to-1 to win the TBJHL championship.  They then played the Dauphin Kings of the MJHL in the Abbott Cup semi-final and defeated them 4-games-to-2.  This advanced them to the Abbott Cup, essentially the final-four of Canadian junior hockey at the time.  Up against the Saskatchewan Junior Hockey League's Weyburn Red Wings, were defeated 4-games-to-2 despite leading 2-games-to-none at one point.  Weyburn ended up losing the Memorial Cup final to the Montreal Junior Canadiens.  During them summer, the Canadian Amateur Hockey Association decided to demote five of the six Junior A league of Western Canada to Tier II Junior A and rename Junior A to Major Junior.  The effected leagues were the BCJHL, AJHL, SJHL, MJHL, and TBJHL.  The only league that was left at the Major Junior level was the rebellious Western Canada Junior Hockey League.  The five remaining leagues were barred from competing for the Memorial Cup, even though, all but the TBJHL, retained the right to the Abbott Cup.  Two leagues remained at Major Junior in Eastern Canada, the Ontario Major Junior Hockey League, formerly known as the OHA, and the Quebec Major Junior Hockey League.  All that remained for Tier II Junior A in Eastern Canada were a couple small leagues in Ontario (SOJAHL, CJHL) and even smaller leagues in the Maritime Provinces.  To balance the power a bit, the CAHA assigned the TBJHL to the Eastern section of the national playdowns for the first time since 1927.
 In 1971, the TBJHL allowed for the expansion of the St. Paul, MN-sponsored Thunder Bay Vulcans.  The Vulcans won the league title in their first season.  In 1972, the St. Paul group were granted the right to create their own league in Minnesota.  They brought the Thunder Bay franchise with them, renaming it the Thunder Bay Centennials, and lured away the Thunder Bay Hurricanes.  For the 1972–73 season, the newly formed Can-Am Junior Hockey League was actually allowed to represent the Thunder Bay district at the National level.  In 1973–74, the Centennials fled the league and were renamed the Thunder Bay Beavers.  The Can-Am league joined USA Hockey and were renamed the Midwest Junior Hockey League.  The only Canadian team that remained was the Hurricanes.  The Hercs competed in the TBJHL playoffs in 1974, despite not being a league member, and won the region against the crowned league champion Fort William Canadiens.  The Hercs returned to the TBJHL full-time for the 1974–75 season.
 In 1976, league expanded to 6 teams with the induction of the Atikokan Voyageurs and Thunder Bay Blades.
 The 1978–79 season began with the merging of the Beavers, Canadians, and Hurricanes into the Degagne Buccaneers and Case Eagles and Blades into the Thunder Bay North Stars.  The Voyageurs folded late in the season and were replaced by the league-bolstered "Rural Voyageurs".  For 1979–80, they were replaced by the Nip-Rock Rangers.  On June 26, 1980, the league was liquidated in favour of a single Jr. An entity in Thunder Bay—the Thunder Bay Kings.  Both the North Stars and Buccaneers went out of business on July 6, 1980, when the TBAHA revoked their Junior A status in favour of what would be the Kings.
 In 1980, the Thunder Bay Kings were created as a powerhouse Junior A team and helped create a new league called the Thunder Bay Hockey League with the Sr. A Thunder Bay Twins, Int. A Thunder Bay Blazers, and CIAU Lakehead Nor'Westers.  In 1984, they were renamed the Thunder Bay Flyers and joined the United States Hockey League.  They won the Anderson Cup as USHL regular season champs in 1988, 1989, 1991, and 1992; the Clark Cup as American Junior A National Champions in 1988 and 1989; the Dudley Hewitt Cup as Central Canadian Champions in 1988, 1989, 1991, 1992, and 1995; the Manitoba Centennial Cup as Canadian Tier II Junior A National Champions in 1989 and 1992.  The Flyers folded in 2000.
 In 2001, the Superior International Junior Hockey League was formed, following in the footsteps of the Thunder Bay Junior A Hockey League.
  
 The winner of the TBJHL Playoffs was awarded the Jack Adams Trophy as Thunder Bay Amateur Hockey Association Junior "A" Champions.  Since this was a branch championship, Champions from the North Shore or Kenora-Fort Frances Leagues were eligible to challenge for it.  The TBJHL Champions probably exclusively won the Bill Fero Trophy as Lakehead Junior Champions.
 Tier II Junior A
 National Champions.
 Champions
 Finalists
 Eastern Canadian Champions.
 Champions
 Finalists
 Western Canadian Champions.
 Champions
 Finalists
 In 1980, the Thunder Bay Junior A Hockey League had been reduced to three teams: the Degagne Buccaneers, Thunder Bay North Stars, and Nip-Rock Rangers or nearby Nipigon, Ontario.  Instead of continuing with the slowly faltering league, the Thunder Bay Amateur Hockey Association decided it would more efficient to form a Citywide superleague with one top-level team from each major level.  In the league would be the Thunder Bay Twins (eligible for the Allan Cup), Thunder Bay Blazers (Hardy Cup), Thunder Bay Kings (Centennial Cup), and Lakehead Nor'Wester (University Cup).
 By 1982 the Blazers merged with the Twins as the Intermediate level was ended by the Canadian Amateur Hockey Association, the Twins moved to the Central Senior Amateur Hockey League in Manitoba, and the Nor'Westers moved into the Ontario University Association.  The League was rearranged into a multi-tier Junior league with the Kings at the Jr. A level, the new Thunder Bay Hornets and Schreiber North Stars at Jr. B, eligible for the newly created Keystone Cup.  Schreiber left after one year and were replaced by the Thunder Bay Maple Leafs.  In 1984, the league was disbanded.  The Kings changed their names to the Flyers and joined the United States Hockey League, the Maple Leafs folded, and the Hornets were promoted to the Manitoba Junior Hockey League.