Final answer:
No, not all pioneers on the Oregon Trail settled in Oregon; many continued on to other destinations. The Willamette Valley in Oregon Territory was a common end point for those who did settle, and the influx of American settlers helped strengthen U.S. claims to the territory.
Step-by-step explanation:
Most Oregon Trail pioneers did not actually settle in Oregon. While over 400,000 settlers traveled the Oregon Trail during the height of migration from 1845 to 1870, the actual number of settlers who remained in Oregon was a fraction of that. Instead, many settlers continued on to other destinations such as California or took alternate routes like the Santa Fe Trail. Those who did arrive in Oregon commonly ended their journey in the Willamette Valley or other parts of the Oregon Territory, which included present-day Washington, Idaho, and parts of British Columbia. The influx of American settlers to the Oregon Territory helped to bolster U.S. claims to the region, particularly in the face of competing British claims.