The numbers do change, even within nearby systems, in part because the systems get bought and sold, and major operators buy systems near theirs and put everything on the same channels.
On a side note, when I first got cable, WGN was on channel 9 (as it is in Chicago) and TBS was on 17 (as it is in Atlanta); they've both been moved a few times. On our system, WGN is on 1, TBS on 25 (and this is a Time Warner system; you'd think they'd give Turner stations a lower spot).
Back to Wof and J - They're also switching stations in Milwaukee, from WTMJ (NBC, Channel 4) to WDJT (which bills itself as CBS-58).