Actually, it's been dead since 1997, and I hadn't noticed until today. There used to be three AAA leagues in the US, the American Association, the International League, and the Pacific Coast League. The first AA was an actual major league in the late 1800's, but was marginalized by the formation of the American League. It kept on as a minor league until 1962, when it finally disbanded as a result of losing too many of its biggest markets (e.g., Milwaukee, Kansas City, Minneapolis and St. Paul, and Houston), to movement and expansion by the majors. It was reformed in 1969 when the majors expanded to twenty-four teams, with the attendant need for four additional AAA teams. In 1997, as part of the big push to make the minor leagues more corporate and less eclectic (the same push that forced the expansion of McCoy Stadium), Bud Selig apparently decided that the AA was no longer needed. My own suspicion is that his oh so nimble mind had trouble with the abbreviation "AA (AAA)" that could be used for the league. The AA disappeared, and its teams were melded into the other leagues, so now you get New Orleans (and Nashville and Memphis, et al.) playing in the Pacific Coast League. Really not a bright boy, our Mr. Selig. They saved a little money on league administration, but now the individual teams have to pay much more for travel. (The IL didn't fare as badly as the PCL in all this. They already had teams in Toledo and Virginia, so the the teams they picked up, such as Indianapolis and Durham, weren't that much further afield.) Ah, progress.
Not that I have any personal stake in this. The only minor league teams I've ever followed were in the IL and PCL, which helps explain why I never noticed the AA was gone. Still, it's a little sad making.