The term "Muckraker" is used to refer to a series of progressively-minded investigative journalists and authors at the turn of the twentieth century. They focused on exposing social and economic injustices, with the intent to affect change in the government policy of the United States. Upton Sinclair wrote his famous book, The Jungle, in 1906. In it he exposed the illicit practices of the meatpacking industry, in both Chicago and the rest of the country. His work caused a public outcry, and he is generally credited with inspiring the passage of the Meat Inspection Act and the Food and Drug Acts through Congress. Sinclair was also an early American socialist.

A speakeasy is an establishment illegally set up to supply alcohol. Speakeasies were particularly influential in American society during the prohibition years, where they served as the only place in America one could go to drink.

Loving v. Virginia was brought before the Supreme Court in 1967. The Lovings were a married couple, one black and one white, who lived in the state of Virginia and were imprisoned for violating the state’s laws against interracial marriage. In a unanimous verdict, the Court ruled that such laws were inherently unequal and unconstitutional. The case overturned the Pace v. Alabama ruling—which had stated, in 1883, that interracial marriage was not protected under the Constitution. 

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.