"Marlene Koenig, a royal genealogist, author of Queen Victoria's Descendants and prolific blogger on the Royal Musings website, says that interest in the wedding reflects an enduring American fascination with Britain and a shared history. "We're a diverse country, but we still look to the United Kingdom because that's where our language and our culture originate. The first royal visit was by the future King Edward VII in 1861 and the first reigning monarch to come here was King George VI in 1939.
"Eleanor Roosevelt ate rationed food off beautiful plates at Buckingham Palace in 1942. This is something that operates on many levels."
And, of course, Prince William's mother became a pop culture icon in America. "For a lot of people, mostly menopausal women, there's the Diana effect," says Mrs Koenig. "The wronged woman, the tragic death, Prince Charles as the ogre and all that."
In 1986, Mrs Koenig camped outside Buckingham Palace for Prince Andrew's wedding to Sarah Ferguson. She can't make it to London this time but will be getting up at 3am to make scones and watch everything as it happens. "