That's a long time -- too long -- for both organizations to be in a drought.
It may be too soon to even consider either team as this season's favorite to win it all, but the early returns on both clubs have been promising. The Original Six teams face off Thursday night at TD Garden in their first meeting of the season.
There are similarities between the Bruins (4-2-0) and the Leafs (5-2-1). In fact, each team has become a little bit better because of the other, and as a result, a rivalry is reborn.
"It's definitely more of a rivalry, more heat going into every game," said Bruins forward Milan Lucic. "We're all looking forward to that challenge and it's going to be a competitive game and we're definitely excited to play."
The current rosters consist of players who at one point or another did or could have played for either team.
The most noticeable one in the past couple of seasons is, of course, Phil Kessel. The high-flying Maple Leafs forward was selected by the Boston Bruins in the first round (fifth pick) in the 2006 NHL draft, and he made a name for himself as a 19-year-old rookie.
Kessel spent three seasons in Boston before general manager Peter Chiarelli traded him to Toronto on Sept. 18, 2009, in exchange for the Maple Leafs' first- and second-round picks in the 2010 draft, plus a first-round pick in the 2011 draft.
Toronto's first-round selection for 2010 turned out to be the No. 2 pick in the draft, and the Bruins used it to select Tyler Seguin, who has already made an impact in Boston.
Following the Bruins' practice at Ristuccia Arena on Wednesday, reporters from both Boston and Toronto were waiting at Seguin's locker stall. The 18-year-old forward said the attention made it feel like draft day.
His career would have taken a completely different route if the Bruins and Leafs hadn't pulled off the trade, and it's possible Seguin would be playing for Toronto instead of Boston on Thursday.
Seguin, a native of Brampton, Ontario, grew up a Leafs fan so playing against his hometown team for the first time in his professional career will be interesting.
"It should be a lot of fun," Seguin said. "It might be a little weird at first, seeing a Leaf jersey on the opposing team.
"Growing up, all I did was want Toronto to win a Cup. Everyone wanted that back then. Everybody had favorite teams, [Toronto] was just my local team. Now I'm going against them."
Kessel struggled while he was in Boston and wanted out. The change of scenery has been good for him. He notched 55 points (30 goals, 25 assists) in 70 games for the Leafs last season, and he's tearing it up offensively this season with 9 points (7 goals, 2 assists) in eight games.
"He's having a pretty good start and hopefully we'll make it hard on him," said Bruins forward David Krejci.
Kessel can be contained during even-strength play, but his offensive skills shine on the power play.
"I haven't had a chance to watch him this year, but he looks great in the highlights," said Bruins defenseman Matt Hunwick. "He's always had the scoring touch and the ability to break the game open. He's getting better as he gets older.
"We know what to expect because we played with him. We'll play him like anyone, but maybe a little harder because it's always fun to play against former teammates. Now that he's on the other side, it's a big challenge for us as a defensive corp. We've shown in the past we're ready for him, and hopefully this season we'll rise to the challenge because he's having a great start. He's a heck of a player."
While all the talk will be about Kessel, there's another Leafs player who probably would have had a positive effect if he were playing in Boston.
Enter Kris Versteeg.
The Bruins selected the highly skilled forward as their fifth-round pick (134th overall) in 2004. He made his pro debut with Boston's AHL affiliate in Providence near the end of the 2005-2006 season.
Krejci joined Versteeg the following winter, and the two were progressing well in their first full season in the AHL. Then, on Feb. 3, 2007, Chiarelli traded Versteeg to the Chicago Blackhawks in exchange for Brandon Bochenski.
There were many in the Bruins' organization who were not pleased with Chiarelli's decision to trade Versteeg, including hockey operations personnel and players. Krejci was among the disappointed.
"He was my first friend who got traded," Krejci said. "But that's how it goes. You meet people and they get traded and you've got to move on. [Thursday] he's going to be my enemy and I'm going to play as hard [against him] as all the other guys."
Versteeg was an important part of the Blackhawks' Stanley Cup championship team last season, but he was traded to the Maple Leafs last June.
Versteeg's talent and success do not surprise Krejci.
"When we played together, he was a great hockey player," Krejci said. "He's smart and he has great hands. He thinks the game very well and he adapted to the NHL very well. I wasn't surprised last year when he won the Stanley Cup."
So Kessel and Versteeg are playing for the Maple Leafs, and Seguin is with the Bruins. But there's another connection between the organizations that could turn out to be the biggest.
On June 24, 2006, the Bruins traded goaltender Andrew Raycroft to the Maple Leafs in exchange for one of Toronto's top prospects -- Tuukka Rask. Leafs fans were livid when the deal was made, especially given that Rask was the organization's first pick (21st overall) in the 2005 draft.
"To be honest, I really didn't care," Rask said with a laugh. "I didn't know anything about Toronto or anything about Boston. I had never been with an organization in the NHL before and [the trade] just happened and it didn't mean anything. It was great to be a part of an NHL organization, but I didn't know anything about any teams."
Rask enjoyed success during his rookie campaign last season, posting a 22-12-5 record with a 1.97 goals-against average and a .931 save percentage. He's part of a solid goaltending tandem in Boston, alongside veteran Tim Thomas, and Rask has a different perspective now on what could have been.
"It's great to be a part of an Original Six team," he said. "The tradition, the city and everything here is great. I'm sure Toronto is good too. You get traded from one great organization to another great organization, and that's something you need to be proud of and appreciate."
If the Bruins and Maple Leafs can build on their early-season success, both teams could earn a postseason berth and maybe even face each other in the race to win a Stanley Cup.
Joe McDonald covers the Bruins and Red Sox for ESPNBoston.com.