Nicola Sacco (pronounced [nikla sakko]; April 22, 1891 August 23, 1927) and Bartolomeo Vanzetti (pronounced [bartolomo vantsetti, -dzet-]; June 11, 1888 August 23, 1927) were Italian immigrant anarchists who were controversially accused of murdering Alessandro Berardelli and Frederick Parmenter, a guard and paymaster respectively, during the April 15, 1920, armed robbery of the Slater and Morrill Shoe Company in Braintree, Massachusetts, United States. Seven years later, they were executed in the electric chair at Charlestown State Prison.

After a few hours' deliberation on July 14, 1921, the jury convicted Sacco and Vanzetti of first-degree murder and they were sentenced to death by the trial judge. Anti-Italianism, anti-immigrant, and anti-Anarchist bias were suspected as having heavily influenced the verdict. A series of appeals followed, funded largely by the private Sacco and Vanzetti Defense Committee. The appeals were based on recanted testimony, conflicting ballistics evidence, a prejudicial pretrial statement by the jury foreman, and a confession by an alleged participant in the robbery. All appeals were denied by trial judge Webster Thayer and also later denied by the Massachusetts Supreme Judicial Court. By 1926, the case had drawn worldwide attention. As details of the trial and the men's suspected innocence became known, Sacco and Vanzetti became the center of one of the largest causes clbres in modern history. In 1927, protests on their behalf were held in every major city in North America and Europe, as well as in Tokyo, Sydney, Melbourne, So Paulo, Rio de Janeiro, Buenos Aires, Dubai, Montevideo, Johannesburg, and Auckland.Celebrated writers, artists, and academics pleaded for their pardon or for a new trial. Harvard law professor and future Supreme Court justice Felix Frankfurter argued for their innocence in a widely read Atlantic Monthly article that was later published in book form. Even the Italian fascist dictator Benito Mussolini was convinced of their innocence and attempted to pressure American authorities to have them released. The two were scheduled to die in April 1927, accelerating the outcry. Responding to a massive influx of telegrams urging their pardon, Massachusetts governor Alvan T. Fuller appointed a three-man commission to investigate the case. After weeks of secret deliberation that included interviews with the judge, lawyers, and several witnesses, the commission upheld the verdict. Sacco and Vanzetti were executed in the electric chair just after midnight on August 23, 1927.Investigations in the aftermath of the executions continued throughout the 1930s and 1940s. The publication of the men's letters, containing eloquent professions of innocence, intensified belief in their wrongful execution. Additional ballistics tests and incriminating statements by the men's acquaintances have clouded the case. On August 23, 1977the 50th anniversary of the executionsMassachusetts Governor Michael Dukakis issued a proclamation that Sacco and Vanzetti had been unfairly tried and convicted and that "any disgrace should be forever removed from their names".

The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, 326 Indian reservations, and nine minor outlying islands. At nearly 3.8 million square miles (9.8 million square kilometers), it is the world's third- or fourth-largest country by geographic area. The United States shares land borders with Canada to the north and Mexico to the south as well as maritime borders with the Bahamas, Cuba, and Russia, among others. With a population of more than 331 million people, it is the third most populous country in the world. The national capital is Washington, D.C., and the most populous city and financial center is New York City.

Paleo-Indians migrated from Siberia to the North American mainland at least 12,000 years ago, and European colonization began in the 16th century. The United States emerged from the Thirteen British Colonies established along the East Coast. Disputes with Great Britain over taxation and political representation led to the American Revolutionary War (1775–1783), which established the nation's independence. In the late 18th century, the U.S. began expanding across North America, gradually obtaining new territories, sometimes through war, frequently displacing Native Americans, and admitting new states. This was strongly related to belief in manifest destiny, and by 1848, the United States spanned the continent from east to west. Slavery was legal in the southern United States until the second half of the 19th century, when the American Civil War led to its abolition. The Spanish–American War and World War I established the U.S. as a world power, and the aftermath of World War II left the United States and the Soviet Union as the world's two superpowers. During the Cold War, both sides fought in the Korean and Vietnam Wars but avoided direct military conflict. They competed in the Space Race, culminating in the 1969 American spaceflight that first landed humans on the Moon. The Soviet Union's dissolution in 1991 ended the Cold War, leaving the United States as the world's sole superpower.

The United States is a federal presidential-constitutional republic with three separate branches of government, including a bicameral legislature. It is a founding member of the United Nations, World Bank, International Monetary Fund, Organization of American States, NATO, and other international organizations. It is a permanent member of the United Nations Security Council. Considered a melting pot of cultures and ethnicities, its population has been profoundly shaped by centuries of immigration. The United States ranks high in international measures of economic freedom, quality of life, education, and human rights; it has low levels of perceived corruption. However, scholars have criticized it for racial, wealth, and income inequality, capital punishment and mass incarceration, and lack of universal health care.The United States is a highly developed country, and its economy accounts for approximately a quarter of global GDP and is the world's largest by GDP at market exchange rates. By value, the United States is the world's largest importer and second-largest exporter of goods. Although its population is only 4.2% of the world's total, it holds over 30% of the total wealth in the world, the largest share held by any country. Making up more than a third of global military spending, it is the foremost military power in the world and a leading political, cultural, and scientific force.