While several factors contributed, Germany's resumption of unrestricted submarine warfare in January 1917 directly threatened American lives and commerce, prompting Congress to declare war in April 1917.

False — The Emancipation Proclamation (1863) only freed enslaved people in Confederate states in rebellion. Slavery was not fully abolished until the 13th Amendment was ratified in December 1865.

The Declaration of Independence was adopted by the Continental Congress on July 4, 1776, declaring the thirteen American colonies free from British rule.

The New Deal (1933–1939) was a series of programs, public works projects, and financial reforms enacted by President Roosevelt to provide relief, recovery, and reform during the Great Depression.

The 19th Amendment, ratified in 1920, granted women the right to vote. The suffrage movement had been fighting for this right since the Seneca Falls Convention of 1848.

In Brown v. Board of Education (1954), the Supreme Court unanimously ruled that racial segregation in public schools violated the Equal Protection Clause of the 14th Amendment. This overturned the 'separate but equal' doctrine from Plessy v. Ferguson (1896) and became a cornerstone of the Civil Rights Movement.