What might explain the fact that seaport cities were important centers of revolutionary activity?

Seaport cities were known to be the center of economic activity during the revolution period. Cities such as Boston, Philadelphia, New York and Charleston had a great influence over other areas. British mercantilist policies also targeted these areas thus making the people more aware of the unfair treatment of their colonizers. 

these civilizations were located around fertile rivers, where they could produce an abundance of crops

i do not believe this was true indefiantly the native americans would have lsot aganist america one they didndt have the resources and allies that america had and 2   indians werent as advanced at the time as they were not 3 americans had the expreince because some of the soliders from other wars fought in that war and were attecked etc