MLB expansion reportedly is not an ‘if' but a ‘when.'

Baseball insider Jeff Passan wrote for ESPN on Tuesday that MLB expansion will happen; it's just a matter of where and when it happens.

“Soon enough, it will be Nashville and Salt Lake City. Or is it Charlotte and Portland? Or maybe Montreal and San Jose? The inevitability is real. Expansion is coming to Major League Baseball. In what form, in what cities, in what year — all of those questions will be answered in time. It's destiny,” Passan wrote.

MLB has been at 30 teams since 1998, the first season in which the Tampa Bay Rays and Arizona Diamondbacks began play. In the more than 25 years since then, no teams have been added or removed from the league, although the Montreal Expos relocated and became the Washington Nationals before the 2005 season. Additionally, the Oakland Athletics owner has also expressed his desire to relocate the club to Las Vegas.

Each potential expansion city mentioned has at least one major professional sports team in the city, and all but Montreal have a Minor League Baseball team in or near the city. Nashville, Salt Lake City, and Charlotte each have Triple-A clubs (the Sounds, Bees, and Knights, respectively), while the San Francisco Giants' Single-A team is located in San Jose, and Hillsboro, a city just west of Portland, has the Hops, a High-A team.

If the Athletics are unable to relocate from Oakland to Las Vegas, Sin City could also be a potential expansion spot for MLB. Long shunned due to its ties to gambling, Vegas has become the home of the NHL's Golden Knights and NFL's Raiders, in addition to being a frontrunner for an NBA franchise when the league expands. The city currently sports the Aviators, the Athletics' Triple-A team.

As is typically the case, the hangups of financing the construction of a stadium could cause any or all of these cities to fall out of contention for an MLB expansion team.