From the Sugar Act of 1764 through the Tea Act of 1773, the British Parliament imposed a variety of taxes upon their American colonies in an effort to raise revenue to offset the enormous debts incurred during the Seven Years' (French and Indian) War. Far more efficiently than raising revenue, these duties raised the indignation of the colonits, contributing more than their share to the alienation that fueled the independence movement.
The Stamp Act became the first direct tax on the American colonies in 1765, levying a fee on all official documents, and thus all legal transactions. The response of the Massachusetts House of Representatives was swift and decisive. On June 6, 1765, they agreed to the motion of James Otis to organize an intercolonial meeting to resist the Stamp Act, and two days later, issued a circular letter to the assemblies of the other colonies. The resulting Stamp Act Congress included 9 of the 13 colonies, and their vigorous protest, coupled with effective boycotts of British goods and the all too often violent response in the streets, led Parliament to withdraw the act in 1766.
Yet in a sign of things to come, Parliament issued their withdrawal of the Stamp Act with an no-nonsense Declaratory Act resserting their authority over all colonial affairs, including taxation. Still seeking ways of extracting additonal revenue from the colonies, in 1767 the Chancellor of the Exchequer Charles Townshend proposed a duty on all imports into the colonies of five key commodities -- lead, paint, glass, paper and tea -- reasoning that such indirect taxation would be less odious. Clearly a misjudgment of the mood in the colonies, the Townshend Duties produced results very similar to the Stamp Act: wide spread protests, sporadic violence, and increasing coordination between radical elements in all 13 colonies. The Non-Importation Agreements in 1768 and 1769 were the a series of boycotts of British imports organized in nearly port city in the 13 colonies, accompanied by, eventually led to repeal of four of five of the Townshend duties in 1770.
The sole Townshend Duty to remain in place after 1770 was the duty on tea, and American radicals continued their boycott of that commodity. With declining revenues for the East India Company, Prime Minister Frederick North was led to recraft the scheme of taxation on tea, the most important features of which were to impose the tax at the point of origin, and to sell the tea in America through consignees who were granted exclusive rights to its retail. The results followed the pattern set in the previous decade of agitation, culminating in the Tea Party in Boston, the impoundment of tea in Charleston, and the successful rejection of tea in Philadelphia and elsewhere. Local resistance, in short, made the Tea Act as much a dead letter as any of its predecessors.
From the guide to the Pennsylvania Stamp Act and Non-Importation Resolutions Collection, 1765-1775, (American Philosophical Society)