who went west in wagon trains and why?
I just picked the Oregon Trail to include in my Google search. See if you gain some insight in reading these different articles:
http://www.google.com/search?hl=en&as_q=who+chose+to+be+pioneers+%22oregon+trail%22&as_epq=&as_oq=&as_eq=&num=10&lr=&as_filetype=&ft=i&as_sitesearch=&as_qdr=all&as_rights=&as_occt=any&cr=&as_nlo=&as_nhi=&safe=images