1821 – Spain ceded Florida to the United States under the Adams-Onís Treaty.
1862 – Congress approved the Militia Act, allowing African Americans to serve in the Union Army during the Civil War.
1881 – Sioux Chief Sitting Bull surrendered to US federal troops in Montana.
1918 – The RMS Carpathia, famous for rescuing survivors of the Titanic, was torpedoed by a German U-boat and sunk.
1945 – President Harry S. Truman approved the use of atomic bombs during World War II.
1955 – Disneyland theme park opened in Anaheim, California.
1975 – Apollo–Soyuz Test Project marked the first joint space mission between the United States and Soviet Union.
1984 – TV broadcaster Vanessa Williams resigned as Miss America after scandalous photos of her were published.
2014 – Malaysia Airlines Flight 17 was shot down over Ukraine, leading to heightened tensions between Russia and Western countries like the United States.
2019 – The World Health Organization declared the Democratic Republic of Congo’s Ebola outbreak a Public Health Emergency of International Concern, prompting US response efforts.