This is from the museum's website:
Miracles and Myths: Mapping the World from 1572 to 1921
Discover how maps made the world "go round." Collector Bill Caras' maps will invite you to marvel at the stunning acuracies, the persistent fantasies and the historical developments detailed in his 40 original maps.
If anyone lives in the area there will also be a free lecture.
Details: Tuesday, March 18, 7pm, Meloy Gallery, PARTV Center: Bill Caras, Map Collector, "Mapping the World from the Mediterranean to Montana"
In any case, the showing might be a nice side-trip, if you are coming to Missoula for the GIS conference.