On what basis area, population or wealth was the number of representatives in the house determined

I think it would be population

the completion of the erie canal spurred the first great westward movement of american settlers, gave access to the rich land and resources west of the appalachians and made new york the preeminent commercial city in the united states.

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.