Laverne & Shirley (CBS, 1976-1983)
A spin-off of "Happy Days," "Laverne & Shirley" starred Penny Marshall and Cindy Williams as its titular women, roommates who worked at a fictitious Milwaukee brewery. Set in the 1960s, it's considerably more goofy (and less influential) than the aforementioned shows, but stands as an forerunning example of the single-gal-in-the-city sitcom nonetheless.  Laverne and Shirley supported themselves financially, and relied on each other emotionally largely over any male characters (the series' primary male characters, Lenny & Squiggy, were more sidekicks than anything else). For two seasons in a row, it was also the highest rated series on television.

Murphy Brown (CBS, 1988-1998)
A full decade after "The Mary Tyler Moore Show" went off the air, it found its truest successor in "Murphy Brown."  Candice Bergen starred as the title character (and won a whopping five Emmys for the role), an investigative journalist and news anchor who enters the series fresh from rehab after suffering from alcoholism. Single and forty-ish, Murphy caused a huge stir outside the show when she became unwed and pregnant.  After the show made it clear Murphy would raise the child alone, then-Vice President Dan Quayle infamously spoke out against the show's disprespect of family values.