The NHL is officially exploring expansion.

The league is opening a formal expansion review process to consider adding new franchises to its 30-team league, Commissioner Gary Bettman announced Wednesday.

Las Vegas, Seattle and Quebec City are the markets that have expressed the most serious interest. A second team in the Toronto area leads the list of additional possibilities for any prospect owner with the likely $500 million expansion fee and a passion for hockey.

"The fact we are going through this process doesn't mean we are going to expand," Bettman said. "All it means is we're going to stop just listening to expressions of interest and take a good, hard look at what they actually mean and represent."

The Board of Governors met in Las Vegas on Wednesday before the NHL Awards and decided that the league will take formal applications for new franchises on July 6, closing the process Aug. 10.

The NHL hasn't decided how many clubs it might add, and it doesn't anticipate expansion before the 2017-18 season, Deputy Commissioner Bill Daly said. Bettman indicated that an expansion fee would be at least $500 million, to be distributed among the existing clubs.

The Board of Governors also formalized the rule changes that were approved Tuesday in a meeting of the league's general managers. The NHL will play three-on-three hockey in overtime this fall, and coaches will be able to challenge certain goal calls on video replay. The NHL also is instituting minor changes to faceoff procedures.

But expansion is the most intriguing prospect for a league that has been at 30 teams since the Columbus Blue Jackets and the Minnesota Wild began play in 2000, with those ownership groups paying $80 million apiece to buy in.

With most teams on relatively stable financial footing and numerous potential owners clamoring for a team, the league is more interested in the lucrative expansion process than relocation of the Arizona Coyotes or any other struggling franchise. Bettman affirmed the NHL's commitment to keeping the Coyotes in the Phoenix area.

Las Vegas appears to be the front-runner in this race. Prospective owner Bill Foley has secured more than 13,200 season-ticket deposits for the multipurpose arena under construction near the Las Vegas Strip, and Bettman doesn't hide the league's intrigue about being the first major pro team in this growing desert town — while also realizing the risk of jumping into another non-traditional market and a gambling mecca.

"We're going to take a deep dive and look at what there is in terms of the interest that's being expressed," Bettman said. "Obviously, Bill Foley got a great response to his season-ticket drive."

Bettman and Daly didn't bother to hide the NHL's keen interest in prosperous Seattle, a hockey-friendly town with no NBA team. But no suitable arena is under construction in the Emerald City.

"Perhaps the process will bring some certainty to the arena situation," Bettman said. "No one has their arena act together yet in Seattle."

Quebec City is another strong candidate, with its Videotron Centre opening later this year in a relatively small market that lost the Nordiques in 1995. Sprawling suburban Toronto has seemed ripe for a second team for years, but the NHL wants to see a serious bid before exploring the thorny issues of territorial rights in the hockey-mad town.

"Sometimes we hear from people in Ontario," Bettman said. "We'll wait and see how much of it is real. Participating in the expansion process isn't easy. You've got to be serious and have serious backing to be able to do it."

Bettman and Daly both shrugged off the idea that new teams would hurt the quality of play.

"I don't think there's any concern at all among our managers or among our ownership groups that there is a lack of talent," Daly said. "I think the level of talent in the league has never been stronger, and all clubs have the ability to have four competitive lines and three D pairs. I don't think talent dilution is a concern at all."

The NHL last expanded in 1999, when it added the Atlanta Thrashers. That franchise struggled both on the ice and at the gate before moving to Winnipeg prior to the 2011-12 season.