It actually makes perfect sense that Downton Abbey is such a hit in the United States. Put simply, there are a few things that many Americans love: British accents, dramatic soap operas, and Dame Maggie Smith (because she was Professor McGonagall in the Harry Potter films).
Set in the early 1900s, the period drama doubles as an intelligent soap opera. There are several “Oh my God” moments that producers of most CW shows could only dream of, but there’s never the sense that the series is guilty pleasure viewing. It surrounds the upper class Crawley family, who live on an estate in Yorkshire, and follows their lives as they’re affected by huge historic events from that time period—e.g., World War I, the sinking of the Titanic, and the Spanish flu.
Had history class been nothing more than Downton Abbey episodes on loop, maybe we’d have paid attention a little bit more.