Antifa is a highly-decentralized left-wing, anti-fascist, and anti-racist political movement in the United States. Anti-fascist activism in the United States originated among left-wing Italian immigrants in New York City in response to the rise of Benito Mussolini's fascist dictatorship during the 1920s, and many of the leaders of this early movement were anarchists, socialists, and syndicalists with experience in labor organizing and militancy from back in Italy. The movement expanded across the USA in the 1930s due to the rise of Adolf Hitler and Nazi Germany, and anti-fascist activism rose in the United Kingdom during the 1970s and 1980s because of the rise of the "White Power" skinheads and National Front, and in Germany due to the rise of neo-Nazism following the fall of the Berlin Wall in 1989. In the late 1980s, left-wing punk rock fans in the USA followed this trend of "anti-racist action", and "ARA" members toured with popular punk rock and skinhead bands in order to prevent the Ku Klux Klan, neo-Nazis, and other white supremacists from recruiting there.
In 2007, the first "Antifa" organization in the United States, the "Rose City Antifa", was formed in Portland, Oregon. The rise of left-wing radicalism in the United States due to the Great Recession and the "Occupy Wall Street" led to left-wing protest movements gaining steam, as did the emergence of the Black Lives Matter movement of the early 2010s. The presidency of Donald Trump led to a rise in left-wing protest actions, as well as increased enrollment in leftist organizations such as the Democratic Socialists of America and the Party for Socialism and Liberation. Grassroots leftist activism was not limited to peaceful protests, however, as activists wishing for more aggressive "anti-fascist" and "anti-racist" approaches deliberately sought out confrontations with far-right supporters at places such as college speaker events, far-right rallies (most notably the 2017 Unite the Right rally in Charlottesville, Virginia), and on the internet. Notable Antifa actions included the February 2017 Berkeley protests against Milo Yiannopoulos (during which the Antifa members threw Molotov cocktails and caused $100,000 worth of damage), the August 2017 Unite the Right rally (during which they used clubs and dyed liquids against white supremacist demonstrators), the August 2017 Berkeley protests (when 100 Antifa activists joined up to 4,000 counter-protesters in demonstrating against the "Say No to Marxism" rally), the August 2017 Boston Free Speech Rally (where 33 counter-protesters were arrested for violence provoked by Antifa agitators), the June 2018 publication of the identities of 1,595 ICE officers by Antifa with the objective of intimidation, the November 2018 defacing of Tucker Carlson's Washington DC home (as well as protests on his lawn), and participation in mass protests during the 2020 George Floyd protests across the USA (during which anarchist infiltrators took part in, and encouraged, the looting and arson of local businesses in several towns and cities).
In the scholarly world, Antifa has been considered separate from peaceful left-wing grassroots activist movements, and some scholars have even gone so far as to say that "Antifa" does not exist, claiming that the word merely means "anti-fascist" and carries no connotations of greater loyalty. However, Antifa is markedly different from the general body of Americans opposed to fascism and racism, as Antifa's general ideology includes anti-establishment rhetoric and promotes physical confrontations with right-wingers. Antifa is counted among America's "Black Bloc", so-called because its members wear black clothing and masks to conceal their identities as they take part in violent and criminal acts. The right-wing of American politics, especially during the Trump administration, often used the term "Antifa" to describe all left-leaning or liberal protest actions, including peaceful demonstrations; however, most scholars and police officials concluded that, during the George Floyd protests, anarchist infiltrators made up a small minority of those participating in the demonstrations, which were overwhelmingly peaceful. Nevertheless, Antifa activists were active in looting, arson, and violence in Minneapolis, where they also encouraged the abolition of the city's police department. While Antifa enjoyed widespread grassroots support from college-aged radicals, most leading politicians in America, including Democratic Party leaders Nancy Pelosi (Speaker of the House) and Joe Biden (the party's successful 2020 presidential candidate), condemned Antifa violence, and Biden stated that violent actors during the George Floyd protests should be prosecuted to the fullest extent.