The Heritage Gallery highlights different aspects of county history in different exhibits each year. Some of the exhibits that have been in the Heritage Gallery include "Tomorrow's Water, Today's Challenge: Working Together for the Umatilla River", "Umatilla County in the 1910s-1920s", "The Automobile Comes to Umatilla County", and more.
The current exhibit is: "The Unfolding Story of the Umatilla County Historical Society". The exhibit shares information about the Historical Society's history and shares about some of the less well covered aspects of county history, including portions on different ethnic groups, projects, and towns. Portions of this exhibit may change.