They moved because in 1837 There was a Saying Called the Panic Days and it had many Americans scared because of Jobs life Farms destroyed with crops so they were running out of Options. Then Oregon had recently Joined the U.S. so people thought of Moving to a New state to try and Start over. Also with the Fact that Texas,California and even going into North Nevada and Colorado Go Conquered People wanted a Way out.
I Hope this Helped a Little
-Dante