I have relatives who migrated to the US and Canada in this period (1830-40). One family went from Co. Down to Ontario, another from Wigtownshire to New York, and a third from Co. Wicklow to Canada. In two cases, they went where others from their communities had preceded them. These people were literate and presumably were responding to encouraging letters sent home by the earlier settlers.
By 1850, they all had moved on to frontier areas of Wisconsin where the gov't. was selling (not giving away) recently opened up land. All three families were young, recently married, with few or no children at the time the emigrated. Evidently they sold whatever they had to pay their passage and stake them to a start in the New World. They probably started out as hired laborers on someone else's land until they could earn enough to get a piece for themselves.
I think that they were probably typical immigrants in this time period - that is, they had some education and a small amount of money; they were not from the very bottom of the social ladder.