Elaborate networks of safe houses and anti-slavery sympathizers that helped slaves to freedom, the Underground Railroad was a first in American civil rights movements, literally.

From 1932 to 1972, the Tuskegee Syphilis Experiment was a study conducted by the U.S. Public Health Service to study the progression of humans infected with untreated syphilis.

In 1911, Americans from Pennsylvania to Maine sweltered under 11 days of a crippling heatwave, long before the advent of air conditioning during New England’s record-breaking heatwave.

Designed to marginalize African Americans by limiting their right to vote, access to good paying jobs and higher education, Jim Crow laws and segregation would take many years, social revolutions, and legal precedents to repeal.

A joint venture between the U.S., Great Britain and Canada, The Manhattan Project resulted in the first successful development of a nuclear bomb.

Remaining the most lethal and destructive riot in American history, the New York City Draft Riots of 1863 started with opposition to Lincoln’s draft and morphed into a race war.

After Mexico refused to sell land to U.S. President Polk, his belief in manifest destiny led to his declaration of war in 1846. The Mexican American War would ultimately last for two years, costing Mexico a lot of lives and land