On April 5, 1764, the British Parliament passed the Sugar Tax on the American colonies. It was introduced by Prime Minister George Grenville. From the article:
"The Sugar Act
Titled The American Revenue Act of 1764
On April 5, 1764, Parliament passed a modified version of the Sugar and Molasses Act (1733), which was about to expire. Under the Molasses Act colonial merchants had been required to pay a tax of six pence per gallon on the importation of foreign molasses. But because of corruption, they mostly evaded the taxes and undercut the intention of the tax — that the English product would be cheaper than that from the French West Indies. This hurt the British West Indies market in molasses and sugar and the market for rum, which the colonies had been producing in quantity with the cheaper French molasses. The First Lord of the Treasury, and Chancellor of the Exchequer Lord Grenville was trying to bring the colonies in line with regard to payment of taxes. He had beefed up the Navy presence and instructed them to become more active in customs enforcement. Parliament decided it would be wise to make a few adjustments to the trade regulations. The Sugar Act reduced the rate of tax on molasses from six pence to three pence per gallon, while Grenville took measures that the duty be strictly enforced. The act also listed more foreign goods to be taxed including sugar, certain wines, coffee, pimiento, cambric and printed calico, and further, regulated the export of lumber and iron. The enforced tax on molasses caused the almost immediate decline in the rum industry in the colonies. The combined effect of the new duties was to sharply reduce the trade with Madeira, the Azores, the Canary Islands, and the French West Indies (Guadelupe, Martinique and Santo Domingo (now Haiti)), all important destination ports for lumber, flour, cheese, and assorted farm products. The situation disrupted the colonial economy by reducing the markets to which the colonies could sell, and the amount of currency available to them for the purchase of British manufactured goods. This act, and the Currency Act, set the stage for the revolt at the imposition of the Stamp Act.