Sacco and Vanzetti were two Italian immigrants who worked as fishmongers in the Boston area in the 1910s and 1920s, who were arrested, tried and convicted for a murder during an armed robbery of a shoe factory in Braintree, MA.

The police investigating the crime began to focus on the Italian immigrant community, particularly the anarchist followers of Luigi Galleani. Sacco and Vanzetti, while having no criminal background, were well known Galleanisti, and were convicted quickly of the crime and sentenced to be executed. A controversy quickly arose about the manner of their trial and conviction, and they became a cause celebre around the country. Despite this, both men were executed on August 23, 1927.

The "Baby Boomers" were the product of the conditions of America in the years immediately after World War II. Many young people had delayed marriage due to the War, and laws like the GI Bill helped many people start careers and families. Between 1946 and 1964, the birth rate grew exponentially. This "Baby Boom" generation helped foment Second Wave Feminisim, the 1960s Counterculture, and the anti-Vietnam movements. 

The Twenty-First Amendment, passed in Congress on February 20, 1933 and ratified by the states on December 5, 1933, served just one function: to repeal the Eighteenth Amendment that enacted Prohibition. Over the 24 years Prohibition had been in effect, it had been a disaster. Alcohol was still pervasive in the country, and its illegal status had merely encouraged a spread in criminal activity producing it. By Franklin Roosevelt's election, the repeal of the Eighteenth Amendment seemed inevitable.

World War II saw a large amount of healthy, working aged men drafted into the armed forces. At the same time, factories were expanding at a rapid rate to supply war materiel for those same armed forces. Stepping into the place of the usual factory workers were large numbers of women, who could not serve in the war effort by fighting.

Beginning in the 1880s, America experienced a massive surge of immigration that swelled its population. Overwhelmingly, these immigrants were peasants and laborers from Southern and Eastern Europe. Italians, Bavarians, Poles, Russians, and Jews from all over Eastern Europe came to America from turmoil and conflict in their native countries. Beginning in the early twentieth century, new immigration laws restricted the entrance of immigrants, which were not changed until mid-century.

Several acts were passed under Lyndon Johnson that promoted liberalism and allowed for the use of public money to fund the arts, tighter controls on pollution, and construction of low income housing.

The Montgomery Bus Boycott began in December 1955 when Rosa Parks protested the practice of African Americans being required to sit in the back portion of public buses.  Led by a young Martin Luther King, Jr. in his first high profile civil rights campaign, the African American community of Montgomery refused to ride public transportation in the city.  In 1956, a Supreme Court ruling ended the Alabama and Montgomery laws enabling segregation in buses.

The Gideon v. Wainwright case was presented to the Supreme Court during the extremely liberal era of Chief Justice Warren. It established that any citizen accused of a crime has the right to legal assistance, even in the event that the citizen is unable to afford the costs. Engel v. Vitale prohibited prayer in public schools. Miranda v. Arizona mandated that law enforcement officials had to inform suspects of their rights prior to questioning. Loving v. Virginia declared laws preventing interracial marriage as unconstitutional. Racial discrimination in property sale and rental was ended by the Civil Rights Act of 1968.

The Civil Rights Movement, which began in the mid-1950s with the Brown v. Board of Education Supreme Court case and the Montgomery Bus Boycott, pursued a variety of methods, including political lobbying, legal arguments, and direct protests. Most notably, the Civil Rights Movement was a non-violent protest movement, led by Dr. Martin Luther King, Jr. on principles established by Mohandas Ghandi in India. The Civil Rights activists, usually multiracial and well trained, eschewed violence in all of their protests.

The Stonewall Inn was a popular gay bar in Manhattan's Greenwich Village that was raided by police on June 28, 1969. While such raids, which were aiming to arrest bar patrons on decency charges, were common in the period, this raid made many people turn on the police and begin to riot. The event is largely seen as one of the key sparks in the gay rights movement, as it was the first time that gay people had stood up against authorities who persecuted them for simply for being homosexuals.