On March 9, 1995, the Arizona Diamondbacks and Tampa Bay Devil Rays were awarded expansion franchises and were green-lighted to start play in the 1998 season.

From virtually that day forward, realignment in MLB has been a complicated, ongoing issue, with grandiose — but ultimately futile — proposals every step of the way. This included a radical plan in 1997 that would have resulted in 15 teams, including the Mariners, switching leagues.

There have been innumerable false steps, and one modest tweak that resulted in the Milwaukee Brewers moving to the National League in 1998. Mostly, however, these efforts have brought strife, and, ultimately, a lack of consensus.

Now, finally, more change is brewing. By the time the owners end their quarterly meeting this week in Milwaukee, it is expected that the Houston Astros, a National League team since their inception as the Colt .45's in 1962, will be switched to the American League, effective 2013.

Of more local interest, they will almost certainly be joining the Mariners in the AL West. That means the M's (as well as the Rangers, Angels and A's) have just one more season to exploit their inclusion in the only division in baseball with four teams.

Houston's anticipated departure from the NL Central in a year will leave the much-tidier alignment of six divisions comprised of five teams each, which should lead to much more equitable scheduling. It will also, of course, lead to an odd number of teams — 15 in each league — which will necessarily be accompanied by an interleague game virtually every day of the season.

Few people remember this, but the Rays (as they are now known) were originally placed in the AL West. But before they had played a game, they were switched to their current spot, the more geographically-sensible AL East.

Commissioner Bud Selig at one point in the late 1990s made significant geographic realignment his pet project. One of the plans that emerged was the aforementioned one in which the Mariners, A's, Angels, Rangers, Royals, Twins, Brewers and White Sox would have moved to the National League, and the Expos, Mets, Phillies, Braves, Reds, Marlins and Pirates would have moved to the American League.

This, along with numerous other equally wild incarnations, got more serious consideration than you'd think; but ultimately enough teams had reservations to keep radical re-alignment from happening. I vividly remember covering the owners meeting in Atlanta in September of 1997 where all this came to a head, and thoroughly enjoying the fireworks that ensued, which included Giants owner Peter Magowan threatening to sue if the A's joined the NL.

The Mariners, at that point, were willing to move to the National League because they thought it would lead to placement in a more geographically-sensible division that would mitigate their travel issues. They were earmarked for an expansive NL West that at one point was to include Anaheim, Arizona, Colorado, Los Angeles, Oakland, San Diego and San Francisco.

"There's just so much to like about it," team president Chuck Armstrong told me back then for a story that ran Aug. 10, 1997. "This year, in particular, we travel more miles than any team in baseball, just a killer schedule. We have strongly been in favor of realignment to put more teams in our division that are in our time zone."

Ultimately, it all fell apart, and MLB settled for Detroit switching from the AL East to AL Central, and Milwaukee moving to the NL Central (after Kansas City declined the first opportunity to do so).

In the ensuing years, other realignment plans have come and gone. In 2000, there was talk of Arizona joining the AL West as part of a wide-ranging proposal that would have landed Texas in the AL Central and Tampa Bay in the National League. That didn't have legs. Later in 2000, the major-league union sent out a memo querying its members about a plan that included the M's moving to the National League, to be replaced in the AL West by — wait for it — the Houston Astros.

The Astros didn't want anything to do with it back then, and it fizzled. Why now? A big reason is that MLB now has a big hammer to compel the move — the impending sale of the team from Drayton McLane to Jim Crane, which is expected to be voted on Thursday.

As part of the approval process — which has been problematic — Crane is believed to have agreed to the switch of leagues, for which he reportedly will be compensated with an $80 million discount in the $680 million purchase price. This is all tied into the expected expansion of the postseason that figures to be a part of a new collective bargaining agreement.

A new CBA is also said to be imminent, and it has been widely reported that it will include a second wild card team in each league, and an extra round of playoffs.

Yes, change is coming — change that has been more than 15 years in the making.

Larry Stone: 206-464-3146 or lstone@seattletimes.com.