What / or who are they: Delaware, Pennsylvania, New York, New Jersey
Why middle: These were the 4 of the 13 original colonies that were between the northern and southern colonies.
Religion: this is the sentence you really like to write. There were all sorts of religions present, but not one of them could dominate. These 4 colonies had Lutherans, Mennonites, Calvinists (mostly Dutch), and Presbyterians.
Commerce: mostly agriculture at the time, but not restricted to 1 crop as the south was. Had good ports and growing cities (New York, Philadelphia). I like to include the well respected intellectual hotbed of people there like Ben Franklin.
The main reason is that neither side was willing to compromise on the idea of taxation. The British need revenue to pay for the French and Indian War, and the colonists were upset that they had no representation in Congress. There was little-to-no room for compromise.
The population of Puerto Rico traces its ancestry in mostly the Spanish colonists and the indigenous people of the island. They have mixed over time and gradually created a mestizo population, which became the dominant population on the island and still is. There are of course some other influences in the gene pool of the Puerto Ricans, with some of it being from the African continent because of the African slaves that were brought, but it is a small minority, and it is also a population that has been heavily mixed.
The Whig party broke up as a consequence of the compromise of 1850.
