Provisional and Territorial Records Guide
Note: The following map is intended to provide researchers with a general understanding of significant county boundary changes over time. Researchers should refer to other sources for more detailed and precise representations.
On the eve of statehood in February, 1859, Oregon Territory was divided into eighteen counties. The territory had an area of 96,981 square miles and a white population of roughly 53,000. Wasco County had an area nearly twice as large as the rest of the territory but its population numbered less than 1500 people.