The Houston Astros switch to the AL West next season, creating two, 15-team leagues. Aside from balancing the leagues each with three, five-team divisions, an Interleague game will be needed on days when all 30 teams play.
The need for this daily AL vs. NL game was one of the reasons it's taken so long for realignment to occur.
Moving Houston to the AL is long overdue. Now, the Astros will have a natural rivalry with the Texas Rangers and no longer are there just four teams in the AL West and six in the NL Central.
But with that comes the Herculean task of scheduling.
Commissioner Bud Selig, speaking Thursday after MLB owners completed quarterly meetings in New York, said work is under way on 2013's schedule that provides for season-long Interleague games.
But what will this do to the popular geographical rivalries, such as Yankees-Mets, Angels-Dodgers, White Sox-Cubs?
Currently, the Interleague schedule calls for 252 games, played in two segments. The first begins this weekend (May 18-20) and the second goes from June 8-24.
The Yankees and Mets, for example, play six times -- three games at Yankee Stadium and three at Citi Field.
It might be impossible to retain the popular six-game series when the schedule is reconfigured for 2013.
Consider this: The nine largest crowds at Citi Field during the first three seasons of the ballpark's existence were the nine games the Yankees played there, an average of 41,513 fans.
Even as Interleague Play has evolved, with a division rotation so that it's not always East vs. East, Central vs. Central or West vs. West, the geographical matchups have remained intact. The Yankees and Mets, for example, have played their home-and home six games since 1999.
To reduce the series to three games would be a mistake. It says here streamlining these popular matchups to accommodate the daily Interleague games would be a minus.
Selig said he hasn't seen a draft schedule for 2013, but added there have been considerable conversations among owners about how it should work. A tentative schedule must be submitted to the players union for approval by July 1.
"I love Interleague Play," Selig said. "It has been very beneficial for the sport. Our fans like it; our customers likes it and it's good. This weekend will be terrific with different matchups, not the normal geographical ones, but good ones."
Selig added "15-15 (two 15-team leagues) will be interesting. I was the last one in on 15 and 15, but I like it now. I'm glad we're doing it."
Interleague Play is beginning its 16th season and obviously, as he says, the paying customers embrace the concept.
In 2011, average Interleague attendance was 33,606, or 12.1 percent higher than the season's final intraleague average of 29,985.
The Yankees hold MLB's best all-time Interleague record of 157-107.
Selig cautions that no decisions have been made, but one format would have the geographical rivals, such as the Yankees and Mets, playing each other six times every three seasons as the schedule rotates between divisions.
Another format would reduce the number of these games from six to three, but these teams would play every year. One scenario would have these rivals playing two games apiece at each stadium.
"I love the natural geographical matchups, I love being at ballparks when these teams are playing," Selig said. "You always want to do the right thing, but when your fans like something you have to be responsive to that and sensitive to it.
"This (will be) a different format. There are a lot of plusses to it, but in the end I'll have to see a schedule and go over it."
Selig was asked if his reluctance to endorse two, 15-team leagues was because of the problem created by the need for a daily Interleague game.
"It wasn't that," he said. "There were a number of things. Surprisingly for somebody who's made as many changes as I have, I'm still a creature of habit. I'm quite satisfied we did it."
The Commissioner mentioned how often he's heard how unfair some of the Interleague matchups have been to certain teams. The flip side is the financial gain these games produce. A good example is attendance at Citi Field when the Mets host the Yankees.
"You have to do what is fair, create the right format and go from there," he said. "Frankly, the Mets and Yankees have never complained to me about it. It's a great rivalry. I can go and on. It's great."
What all this boils down it is Interleague Play has been enormously successful. It would be a pity to damage it.
Hal Bodley is the senior correspondent for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.