Was the Mafia ever involved in the Lehigh Valley (Allentown/Easton/Bethlehem area) in Pennsylvania? If so, which families had crews/guys up there in which rackets?

Bufalino, I would assume.

Definitely Bufalino and of course that one guy Gratti who tried shaking down Michael Scott for an "insurance" situation

Bufalino crew had that area covered. I also believe the Philly family had a few men operating up that way on occasion.

After Bufalino, Billy D'Elia (who had been Bufalino's driver and whose son Russ is named after Bufalino), who is still alive. Scranton also had Louis DeNaples--I think D'Elia testified against DeNaples when DeNaples was trying to keep his casino in the Poconos.

Yes, basically Lou DeNaples was a very wealthy legitimate businessman who sometimes allied with Pittston mob guys to further their mutual goals.

D'Elia became a big shot in the Pittston crew after Bufalino died. D'Elia also became a rat as soon as he got snagged by the feds. Another would-be tough guy down the drain!