Territorial Timeline
Clark County established by the Oregon Provisional Government on August 20, 1845 and includes all of present-day Washington
When the Oregon Provisional Government was established on July 5, 1843, the convention also took steps to divide the huge territory into districts (or counties, as they were re-designated on December 22, 1845). On August 20, 1845 Vancouver District was created, encompassing all of the land north of the Columbia, west of the Rockies and south of Alaska. On September 3, 1849 the borders were modified and the district became re-named Clark County (after William Clark of Lewis and Clark fame). For a short time Clark County included all of present-day Washington.