Sitcoms for Social Action
The sitcom doesn't get much respect. It would be hard to pick out a more reviled art form. If one were to pick out the most important steps towards gay rights in the US,however, I'm pretty sure that American sitcoms deserve one of the very first places. Above Stonewall, gay rights parades and other demonstrations that probably made more enemies than friends. Will and Grace and Modern Family were transformative.
I would suspect that they played an important role in civil rights as well.