When did Washington University change their name to Washington University in St. Louis? This seems a little weird to me. I usually refer to it as Washington University - St. Louis.
The name change was made official 35 years ago, in 1976. From a WUSTL webpage about the two co-founders, Crow and Eliot: Presumably the pre-1976 name of "Washington University" was subject to confusion with other schools, like "University of Washington", "Washington State University", "Washington College", and "George Washington University".
There is a book published in 1978 titled Washington University in St. Louis : its design and architecture, so it has been in use at least since then.