Who determines where you go on a book tour?

The short answer is the publisher, but it’s actually the publicity office of Tor, which takes into account where I’ve toured in the past, when I last visited an area, if ever, and how fantasy and science fiction books sell in a possible tour city or locale. As a practical matter, they won’t schedule tours in places where bookstores are few and far between, or where turnout has been abysmal in the past, either for me or for other F&SF authors. Also, given the hard economic times facing publishers, tours are generally getting to be less frequent and shorter.