The Triangular Trade and Middle Passage.
The 17th and 18th Centuries brought upon new methods of trading due to an increase in technology and navigation but most importantly due to a new found demand for labor. In Europe, empires were struggling to have a sustainable work force present in the New World. The indigenous workers proved susceptible to disease and insufficient in the fields given the conditions of work necessary for profitable production. The work force that was craved in order to support these labor intensive crops could be found in Africa. The Africans were more immune to some diseases that were wiping out the current indigenous workers in the New World, and were also much better workers in the harsh field conditions. Henceforth, the European craving for specific, labor intensive goods from their colonies in the New World, which therefore required a massive, proficient work force; gave way to the idea of the "Triangular Trade", whose hypotenuse was nicknamed the "Middle Passage".
The idea of the Triangular Trade was developed primarily by ship captains from England and New England. The central idea was to have a trade route between three continents, thus forming the "triangle". This idea proved successful because each continent lacked a good which another continent had within its borders. The trading system developed was a rough idea, not a set in stone agreement. Henceforth, sometimes the order in which sea captains traveled the seas varied. However, the conventional path of travel was as follows: New England to Africa back to the West Indies, then to New England, then to Europe. Shippers and traders took this path because the Americas provided goods such as lumber and flour and some manufactured goods which Africa lacked. In turn, the New World gained African slaves; which the New World obviously lacked. This second leg was referred to as the Middle Passage because it served as the middle route between the two legs of the triangle.