Location, Location, Location
From the beginning of The Tonight Show Starring Johnny Carson through the year 1972, the show was film in 30 Rockefeller Plaza in NYC. Afterwards, the location was moved to Burbank, California to an NBC studio, where it was filmed until the show ended in 1992.
A Comedy Mentor
Johnny Carson liked to invite up and coming comedians to appear on The Tonight Show, and he felt like a mentor for them. He gave comedians like Joan Rivers, Jim Carey, Jerry Seinfeld, and Ellen Degeneres a platform early on in their careers.