The Whiskey Rebellion (also known as the Whiskey Insurrection) was a violent tax protest in the United States beginning in 1791 and ending in 1794 during the presidency of George Washington. The so-called "whiskey tax" was the first tax imposed on a domestic product by the newly formed federal government. The "whiskey tax" became law in 1791, and was intended to generate revenue to pay the war debt incurred during the American Revolutionary War. Farmers of the western frontier were accustomed to distilling their surplus rye, barley, wheat, corn, or fermented grain mixtures to make whiskey. These farmers resisted the tax.

Throughout western Pennsylvania counties, protesters used violence and intimidation to prevent federal officials from collecting the tax. Resistance came to a climax in July 1794, when a US marshal arrived in western Pennsylvania to serve writs to distillers who had not paid the excise. The alarm was raised, and more than 500 armed men attacked the fortified home of tax inspector John Neville. Washington responded by sending peace commissioners to western Pennsylvania to negotiate with the rebels, while at the same time calling on governors to send a militia force to enforce the tax. Washington himself rode at the head of an army to suppress the insurgency, with 13,000 militiamen provided by the governors of Virginia, Maryland, New Jersey, and Pennsylvania. The leaders of the rebels all fled before the arrival of the army, and there was no confrontation. About 150 men were arrested, but only 20 held for trial in Philadelphia, and only two were convicted (eventually pardoned).

The Whiskey Rebellion demonstrated that the new national government had the will and ability to suppress violent resistance to its laws, though the whiskey excise remained difficult to collect. The events contributed to the formation of political parties in the United States, a process already under way. The whiskey tax was repealed in 1802 during the Jefferson administration.

A new U.S. federal government began operating in 1789, following the ratification of the United States Constitution. The previous central government under the Articles of Confederation had been unable to levy taxes; it had borrowed money to meet expenses and fund the Revolutionary War, accumulating $54 million in debt. The state governments had amassed an additional $25 million in debt. Secretary of the Treasury Alexander Hamilton sought to use this debt to create a financial system that would promote American prosperity and national unity. In his Report on Public Credit, he urged Congress to consolidate the state and national debts into a single debt that would be funded by the federal government. Congress approved these measures in June and July 1790.

A source of government revenue was needed to pay the respectable amount due to the previous bondholders to whom the debt was owed. By December 1790, Hamilton believed that import duties, which were the government's primary source of revenue, had been raised as high as feasible. He therefore promoted passage of an excise tax on domestically produced distilled spirits. This was to be the first tax levied by the national government on a domestic product. The transportation costs per gallon were higher for farmers removed from eastern urban centers, so the per-gallon profit was reduced disproportionately by the per-gallon tax on distillation of domestic alcohol such as whiskey. The tax applied to all distilled spirits, but consumption of American whiskey was rapidly expanding in the late 18th century, so the excise became widely known as a "whiskey tax". Taxes were politically unpopular, and Hamilton believed that the whiskey excise was a luxury tax and would be the least objectionable tax that the government could levy. In this, he had the support of some social reformers, who hoped that a "sin tax" would raise public awareness about the harmful effects of alcohol. The whiskey excise act, sometimes known as the "Whiskey Act", became law in March 1791. George Washington defined the revenue districts, appointed the revenue supervisors and inspectors, and set their pay in November 1791.

The population of Western Pennsylvania was 75,000 in 1790. Among the farmers in the region, the whiskey excise was immediately controversial, with many people on the frontier arguing that it unfairly targeted westerners. Whiskey was a popular drink, and farmers often supplemented their incomes by operating small stills. Farmers living west of the Appalachian Mountains distilled their excess grain into whiskey, which was easier and more profitable to transport over the mountains than the more cumbersome grain. A whiskey tax would make western farmers less competitive with eastern grain producers. Additionally, cash, which at this time consisted of specie (gold and silver coins), was always in short supply on the frontier, nevertheless the law explicitly stipulated the tax could only be paid in specie. In lieu of specie, whiskey often served as a medium of exchange, which for poorer people who were paid in whiskey meant the excise was essentially an income tax that wealthier easterners did not have to pay. Many of the resisters were war veterans who believed that they were fighting for the principles of the American Revolution, in particular against taxation without local representation, while the federal government maintained that the taxes were the legal expression of Congressional taxation powers.

Small-scale farmers also protested that Hamilton's excise effectively gave unfair tax breaks to large distillers, most of whom were based in the east. There were two methods of paying the whiskey excise: paying a flat fee (per still) or paying by the gallon. Large distilleries produced whiskey in volume and could afford the flat fee. The more efficient they became, the less tax per gallon they would pay (as low as 6 cents, according to Hamilton). Western farmers who owned small stills did not typically have either enough time nor enough surplus grain to operate them year-round at full capacity, so they ended up paying a higher tax per gallon (9 cents), which made them less competitive. The regressive nature of the tax was further compounded by an additional factor: whiskey sold for considerably less on the cash-poor Western frontier than in the wealthier and more populous East. This meant that, even if all distillers had been required to pay the same amount of tax per gallon, the small-scale frontier distillers would still have to remit a considerably larger proportion of their product's value than larger Eastern distillers. Less-educated farmers, who in this era were often illiterate, also feared they would be cheated by corrupt tax collectors. Small-scale distillers believed that Hamilton deliberately designed the tax to ruin them and promote big business, a view endorsed by some historians. However, historian Thomas Slaughter argued that a "conspiracy of this sort is difficult to document". Whether by design or not, large distillers recognized the advantage that the excise gave them and they supported it.

Other aspects of the excise law also caused concern. The law required all stills to be registered, and those cited for failure to pay the tax had to appear in distant federal courts, rather than local courts. The only federal courthouse was in Philadelphia, some 300 miles (480 km) away from the small frontier settlement of Pittsburgh. From the beginning, the federal government had little success in collecting the whiskey tax along the frontier. Many small western distillers simply refused to pay the tax. Federal revenue officers and local residents who assisted them bore the brunt of the protesters' ire. Tax rebels harassed several whiskey tax collectors and threatened or beat those who offered them office space or housing. As a result, many western counties never had a resident federal tax official.