The Stamp Act of 1765 (Duties in American Colonies Act 1765; 5 George III, c. 12) was an act of the Parliament of Great Britain which imposed a direct tax on the British colonies in America and required that many printed materials in the colonies be produced on stamped paper produced in London, carrying an embossed revenue stamp. Printed materials included legal documents, magazines, playing cards, newspapers, and many other types of paper used throughout the colonies, and it had to be paid in British currency, not in colonial paper money.The purpose of the tax was to pay for British military troops stationed in the American colonies after the French and Indian War, but the colonists had never feared a French invasion to begin with, and they contended that they had already paid their share of the war expenses. They suggested that it was actually a matter of British patronage to surplus British officers and career soldiers who should be paid by London.

The Stamp Act was very unpopular among colonists. A majority considered it a violation of their rights as Englishmen to be taxed without their consentconsent that only the colonial legislatures could grant. Their slogan was "No taxation without representation". Colonial assemblies sent petitions and protests, and the Stamp Act Congress held in New York City was the first significant joint colonial response to any British measure when it petitioned Parliament and the King.

One member of the British Parliament argued that the American colonists were no different from the 90-percent of Great Britain who did not own property and thus could not vote, but who were nevertheless "virtually" represented by land-owning electors and representatives who had common interests with them. Daniel Dulany, a Maryland attorney and politician, refuted this in a widely read pamphlet by pointing out that the relations between the Americans and the English electors were "a knot too infirm to be relied on" for proper representation, "virtual" or otherwise. Local protest groups established Committees of Correspondence which created a loose coalition from New England to Maryland. Protests and demonstrations increased, often initiated by the Sons of Liberty and occasionally involving hanging of effigies. Very soon, all stamp tax distributors were intimidated into resigning their commissions, and the tax was never effectively collected.Opposition to the Stamp Act was not limited to the colonies. British merchants and manufacturers pressured Parliament because their exports to the colonies were threatened by boycotts. The Act was repealed on 18 March 1766 as a matter of expedience, but Parliament affirmed its power to legislate for the colonies "in all cases whatsoever" by also passing the Declaratory Act. A series of new taxes and regulations then ensuedlikewise opposed by the Americans. The episode played a major role in defining the 27 colonial grievances that were clearly stated within the text of the Indictment of George III section of the United States Declaration of Independence, enabling the organized colonial resistance which led to the American Revolution in 1775.

The American Revolution was an ideological and political revolution that occurred in British America between 1765 and 1791. The Americans in the Thirteen Colonies formed independent states that defeated the British in the American Revolutionary War (1775–1783), gaining independence from the British Crown, establishing the constitution that created the United States of America, the first modern constitutional liberal democracy.American colonists objected to being taxed by the British Parliament, a body in which they had no direct representation. Before the 1760s, Britain's American colonies had enjoyed a high level of autonomy in their internal affairs, which were locally governed by colonial legislatures. The passage of the Stamp Act of 1765 imposed internal taxes on official documents and newspapers printed in the colonies, which led to colonial protest, and the meeting of representatives of several colonies in the Stamp Act Congress. Tensions relaxed with the British repeal of the Stamp Act, but flared again with the passage of the Townshend Acts in 1767. The British government deployed troops to Boston in 1768 to quell unrest, leading to the Boston Massacre in 1770. The British government repealed most of the Townshend duties in 1770, but retained the tax on tea in order to symbolically assert Parliament's right to tax the colonies. The burning of the Gaspee in Rhode Island in 1772, the passage of the Tea Act of 1773 and the Boston Tea Party in December 1773 led to a new escalation in tensions. The British responded by closing Boston Harbor and enacting a series of punitive laws which effectively rescinded Massachusetts Bay Colony's privileges of self-government. The other colonies rallied behind Massachusetts, and twelve of the thirteen colonies sent delegates in late 1774 to form a Continental Congress for the coordination of their resistance to Britain. Opponents of Britain were known as Patriots or Whigs, while colonists who retained their allegiance to the Crown were known as Loyalists or Tories.

Open warfare erupted when British regulars sent to capture a cache of military supplies were confronted by local Patriot militia at Lexington and Concord on April 19, 1775. Patriot militia, joined by the newly formed Continental Army, then put British forces in Boston under siege by land and their forces withdrew by sea. Each colony formed a Provincial Congress, which assumed power from the former colonial governments, suppressed Loyalism, and contributed to the Continental Army led by Commander in Chief General George Washington. The Patriots unsuccessfully attempted to invade Quebec and rally sympathetic colonists there during the winter of 1775–76.

The Continental Congress declared British King George III a tyrant who trampled the colonists' rights as Englishmen, and they pronounced the colonies free and independent states on July 4, 1776. The Patriot leadership professed the political philosophies of liberalism and republicanism to reject rule by monarchy and aristocracy. The Declaration of Independence proclaimed that all men are created equal, though it was not until later centuries that constitutional amendments and federal laws would increasingly grant equal rights to African Americans, Native Americans, poor white men, and women.

The British captured New York City and its strategic harbor in the summer of 1776, which they held for the duration of the war. The Continental Army captured a British army at the Battle of Saratoga in October 1777, and France then entered the war as an ally of the United States, expanding the war into a global conflict. The British Royal Navy blockaded ports and captured New York City for the duration of the war, and other cities for brief periods, but they failed to destroy Washington's forces. Britain also attempted to hold the Southern states with the anticipated aid of Loyalists, and the war moved south. British general Charles Cornwallis captured an American army at Charleston, South Carolina in early 1780, but he failed to enlist enough volunteers from Loyalist civilians to take effective control of the territory. Finally, a combined American and French force captured Cornwallis' army at Yorktown in the fall of 1781, effectively ending the war. The Treaty of Paris was signed on September 3, 1783, formally ending the conflict and confirming the new nation's complete separation from the British Empire. The United States took possession of nearly all the territory east of the Mississippi River and south of the Great Lakes, with the British retaining control of northern Canada, and Spain taking back Florida.

Among the significant results of the war were American independence and the end of British mercantilism in America, opening up worldwide trade for the United States - including with Britain. Around 60,000 Loyalists migrated to other British territories, particularly to Canada, but the great majority remained in the United States. The Americans soon adopted the United States Constitution, replacing the weak wartime Confederation and establishing a comparatively strong national government structured as a federal republic, which included an elected executive, a national judiciary, and an elected bicameral Congress representing states in the Senate and the population in the House of Representatives. It is the world's first federal democratic republic founded on the consent of the governed. Shortly after a Bill of Rights was ratified as the first ten amendments, guaranteeing fundamental rights used as justification for the revolution.