They promise to be the biggest world junior hockey championships ever.

Hockey Canada announced Thursday that the 2015 and 2017 championships will be co-hosted by Canada's two largest cities — Toronto and Montreal.

"We're taking this to a whole new level," Hockey Canada president Bob Nicholson said.

News conferences were held a few hours apart in both cities for the tournaments that organizers expect to set records for attendance and revenue.

Both cities will host a preliminary round group at each event, with Toronto hosting the medal round in 2015 and Montreal hosting the medal round in 2017.

Team Canada will be based in Montreal for the round robin in 2015, and in Toronto in 2017.

Canada has also been confirmed as host of the 2019 and 2021 tournaments. They wanted to start that run with an extravaganza.

Hockey Canada set aside the normal bidding process to work out a complex deal with the Montreal Canadiens and Toronto Maple Leafs, two provincial governments and the three major junior leagues to hold the tournaments in the two Original Six cities.

"This was a different process than we've had before and the reason is that we have the '15, '17, '19 and '21 world juniors," said Nicholson. "Both Montreal and Toronto have been in the bids before.

"When we started discussions with the Canadiens and Maple Leafs, we knew this was the direction we wanted to go."

The two events will coincide with other celebrations, including the 100th anniversaries of both the Maple Leafs and Hockey Canada, the 150th anniversary of Canada's confederation, the 50th of Montreal's Expo 67 and the 375th of the founding of Montreal.

"It'll be exciting to have world calibre junior hockey played right here," said Canadiens owner and president Geoff Molson. "For Montreal, it's going to be great exposure and also a big economic benefit."

Montreal hosted a world junior tournament once, when Slava Fetisov's Soviet Union won gold and a 16-year-old Wayne Gretzky led Canada to a bronze medal at the old Forum in 1978.

Toronto has never hosted the event.

The tournament will be played at the 21,273-seat Bell Centre in Montreal and at Air Canada Centre in Toronto, which seats 18,819 for hockey but can hold 19,746 with standing room.

Packed arenas

They hope to top the record of 444,718 fans at the 2012 world juniors in Calgary and Edmonton, which netted a $21-million profit that was shared by various hockey organizations.

But Nicholson doesn't just want sold-out games. He wants the seats to be filled with fans. They hope to find a ticket sales system that will ensure maximum attendance, although the NHL clubs' season ticket holders will have to be appeased.

Tim Leiweke, president of Maple Leaf Sports and Entertainment, said there were many complex issues, including conflicts of sponsorships among the various organizations, that had to be resolved.

"There were a lot of behind-the-scenes negotiations to try to sort this out," he said. "It would have been an easy one to fall apart.

"There were probably 20 things that could have killed this deal and I think both organizations did a good job of fighting through the issues. We're not just getting this for the first time in Toronto. This is going to be the centrepiece for our 100th anniversary."

The Canadian Sport Tourism Alliance evaluated the economic impact of the 2012 event at $86 million, although there is much debate on the accuracy of economic spinoff estimates. Nicholson said benefits from the Montreal and Toronto tournaments could top $200 million combined.

"If we do this right, with all the other platforms, $200 million might be a soft number," he said. "We feel it can get higher than that, especially if we package the tickets in a different way.

"We're going to be creative about that to make sure that as many people as possible get in to see this. We left 185,000 people on the outside looking in at Calgary and Edmonton, so is there a way to get more into the games?"

Hockey Canada also announced a 10-year broadcasting extension with TSN and RDS. Nicholson said the upcoming junior championships had no bearing on the extension.

This will mark the 11th and 12th times Canada has hosted the tournament, which starts around Christmas.

While it was once held in smaller centres known for supporting junior hockey, the trend in recent years is to boost revenue by staging it in bigger cities. Nicholson expects that to continue, but said pre-tournament games will be held in major junior arenas.

Hockey development

After Montreal in 1978, it was held in Hamilton in 1986, Saskatoon in 1991, Red Deer, Alta., in 1995, Winnipeg in 1999, Halifax in 2003, Vancouver, Kamloops and Kelowna, B.C. in 2006, Ottawa in 2009 and Regina and Saskatoon in 2010.

Profits from the tournament go into developing hockey across Canada, while visiting teams also benefit.

Attendance at games not involving Team Canada averaged 14,500 in Calgary and Edmonton and they hope to beat that number in Montreal and Toronto.

Nicholson sees it as a key event for growing interest in the sport.

"This is about growing our partnership with the [junior leagues] and getting more young boys and girls involved in our game,"he said. "The demographics in our country have changed and this is going to be a great opportunity.

"We have a lot of immigrants coming to our country and we want to make sure they want to be part of the hockey culture in Canada."

There was no immediate word on ticket pricing plans.

"We haven't even looked into ticket prices but we've always made sure that we have tickets affordable for young kids to watch the game," Nicholson said.