Oregon Bill of 1848 , officially titled when approved , " An Act to Establish the Territorial Government of Oregon , " was an act of Congress to turn Oregon into an official U.S. Territory . The bill was passed on August 14 , 1848 . It was enacted by the 30th United States Congress , and signed by President James K. Polk . The bill came into question several years after the Oregon Treaty . For two years following that treaty , the United States paid little attention to it until news of the Whitman massacre reached Congress . This provided the impetus to formally establish the Territorial Government of Oregon . The Act created a territory that encompassed present-day Idaho , Oregon , and Washington ; as well as parts of Montana and Wyoming
Whitman massacre
Whitman massacre
Oregon Bill of 1848