I remember that just when I turned 18 they raised the drinking age to 19 and then when I became 19 they raised it to 21 (New York).
I was on the other side of that coin. The year I turned 19 in March the drinking age in Virginia went to 19 in July. Then it moved to 20 shortly after I tuned 20, and 21 shortly after I turned 21.
Of course, in Virginia, the drinking age was already 21 for distilled spirits, so the changes were for beer and wine.