Merchants purchased raw sugar (often in its liquid form, molasses) from plantations in the Caribbean and shipped it to New England and Europe, where it was sold to distillery companies that produced rum.

[1] The first leg of the triangle was from a European port to Africa, in which ships carried supplies for sale and trade, such as copper, cloth, trinkets, slave beads, guns and ammunition.

The Molasses Act 1733 provided: ... there shall be raised, levied, collected and paid, unto and for the use of his Majesty ..., upon all rum or spirits of the produce or manufacture of any of the colonies or plantations in America, not in the possession or under the dominion of his Majesty ..., which at any time or times within or during the continuance of this act, shall be imported or brought into any of the colonies or plantations in America, which now are or hereafter may be in the possession or under the dominion of his Majesty ..., the sum of nine pence, money of Great Britain, ... for every gallon thereof, and after that rate for any greater or lesser quantity: and upon all molasses or syrups of such foreign produce or manufacture as aforesaid, which shall be imported or brought into any of the said colonies or plantations ..., the sum of six pence of like money for every gallon thereof ... ; and upon all sugars and paneles of such foreign growth, produce or manufacture as aforesaid, which shall be imported into any of the said colonies or plantations ... a duty after the rate of five shillings of like money, for every hundred weight Avoirdupois.

Molasses from the British West Indies, which was used in New England for making rum, was priced much higher than its competitors and they also had no need for the large quantities of lumber, fish, and other items offered by the colonies in exchange.

[4] Historian John C. Miller noted that the tax: ... threatened New England with ruin, struck a blow at the economic foundations of the Middle colonies, and at the same time opened the way for the British West Indians—whom the continental colonists regarded as their worst enemies—to wax rich at the expense of their fellow subjects on the mainland.Largely opposed by colonists, the tax was rarely paid, and smuggling to avoid it was prominent.

After a brief effort to enforce the act in Massachusetts in the 1740s, the English government tacitly accepted defeat and foreign molasses was smuggled into the Northern colonies in an ever-increasing quantity.