Same thing confused me some years ago when on a company outing to the Bowie Baysox. So I looked it up.
Rule 4.10 of the Official Baseball Rules states in pertinent part that “National Association leagues [i.e., the minor leagues] may adopt a rule providing that one or both games of a doubleheader shall be seven innings in length.” Presumably the South Atlantic League has established such a rule.
–Cliffy
That was the rule I remember from the PCL. I don’t know if it’s still in effect, as I stopped going to lots of Dukes games in the mid-90s and have only been to a couple games in the last decade, none of them doubleheaders. It’s a shame, by the way, that there are no longer minor-league teams in Canada.
In college I went to our baseball games pretty regularly, and we had several double headers each season, and both games went just six innings. It still made for a pretty long day
There is one left, actually, the Vancouver Canadians.
Winnipeg also has a team in the unaffiliated Northern League.