I’ll give you a few to choose from:
-There were plenty of jobs (but low-paying) in America
-Gold Rush
-America had an open door policy (at least until the immigration act)
-Social mobility was possible (unlike restrictive social classes in England)
Assuming you're referring to the "French and Indian War", the outcome was significant since it led to the British heavily taxing the colonists in order to pay for the war (which they won), which led to the American Revolution.
D, some states now allowed slavery and some didn't