Actress-singer Joan O’Brien, who starred with Cary Grant and Tony Curtis in “Operation Petticoat” and was Elvis Presley’s love interest in “It Happened at the World’s Fair,” has died. She was 89.

It’s hard to believe, but even after writing hundreds of articles about classic TV, this is my very first one about Petticoat Junction. I’m not sure why it took me so long to get around to it, because ...