I keep using the word “upheaval” in reference to the changes that minor league baseball experienced to start the 1963 season, and thought it would be a better idea to provide this explainer page rather than explaining it ad nauseum in other posts.

Let’s start with this quote from the Encyclopedia of Minor League Baseball:

“The face of minor league baseball changed in 1963. Gone were hundreds of cities that had been part of Organized Baseball little more than a decade before. Gone were Class B, C and D. And, after 61 continuous years of operation, the American Association was gone, the first Triple-A league to fold.”

In one year, the minors lost two affiliated leagues, and changed the designations of most leagues, particularly in the lower minors. In terms of the overall structure of the minors, it could be argued that the difference from 1962 to 1963 was more significant than the difference between 1963 to present day. This change is the biggest one-year upheaval in the history of the minors, and as such, it makes for an important check point.