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. 

the dominoes began to fall. the surrender at appomattox took place a week later on april 9. while it was the most significant surrender to take place during the civil war, gen. robert e. lee, the confederacy's most respected commander, surrendered only his army of northern virginia to union gen. ulysses s. grant

explanation: