No, Tom Petty did not have anything to do with this show, in case you wonder.
The American Girls (plural, as opposed to Petty's "American Girl" in the singular) was one of a number of female-centric dramas the networks introduced in the late 70's, not quite in the mold of, say, Charlie's Angels, which was entering its 3rd year on ABC, but the idea was that this wasn't about jiggle TV. And that might've been the show's downfall after all.
Producer Harve Bennett left Universal after The Six Million Dollar Man was cancelled, and made a brief stop at Columbia to develop this series before moving on to Paramount and the Star Trek movie series. The idea revolved around a pair of news-magazine researchers whose penchant for getting into trouble provided the drama. Debra Clinger, fresh from the Saturday morning series, The Krofft Supershow, co-starred with Priscilla Barnes, later of Three's Company.
I regret to say I have little memory of seeing any episodes of the series. Its biggest problem was that it aired opposite Aaron Spelling's Love Boat on ABC. Enough said.
Right now, let's scope out this promo, taken from CBS' Fall Preview special for 1978, and narrated by Dick Tufeld (ex-Lost in Space).