1. On December 11, 1787, Patrick Gass was born in Falling Springs, Pennsylvania. Gass is best known for being the last surviving member of the Lewis and Clark Expedition, which explored the western portion of the United States from 1804 to 1806.

2. In 1866, the Dakota Territory was established, encompassing present-day South Dakota, North Dakota, and parts of Montana and Wyoming. The territory existed until 1889, when North and South Dakota became separate states.

3. On December 11, 1890, the infamous Wounded Knee Massacre took place on the Pine Ridge Indian Reservation in South Dakota. U.S. soldiers opened fire on a group of Lakota Sioux, killing more than 150 men, women, and children.

4. In 1925, the city of Deadwood, South Dakota, was hit by a devastating fire that destroyed most of its downtown area. The fire started in a casino and quickly spread, leveling buildings and killing several people.

5. On December 11, 1941, just days after the Japanese attack on Pearl Harbor, German aircraft sank the U.S. freighter SS Cynthia Olson off the coast of South Dakota. The attack was the first enemy action on U.S. soil during World War II.