On this day in 1881 President James Garfield was shot in the back by Charles Guiteau. Guiteau was an unhappy office-seeker who was possibly insane. He shot the president while he was waiting for a train in Washington D.C. Garfield didn't die until September 19th. Many believe it was actually poor work done by his doctors that actually killed him.
On this day in 1964 President Lyndon Johnson signed the Civil Rights Act into law. It was a landmark piece of legislation in that it was the federal government putting forth it's own views onto states that didn't necessarily agree with them. It made it unlawful to discriminate against anyone based solely on race, overturning many "Jim Crow" laws put forth to keep blacks as secondary citizens in the south.
On this day in 1839 the mutiny on board the slave ship Amistad occurred. While being transported to a plantation in Cuba the slaves were able to kill the captain of the ship and take it over. They ordered the owners of the ship to take them back to Africa. But instead they were captured by a US vessel and taken to New York. After many trials it was ruled that slaves were taken illegally and were freed. Many would return to their homes with the help of abolitionists.
On this day in 1937 Amelia Earhart disappeared. She and her navigator were trying to fly around the world. She may have been spying for the US government while making this attempt, but nothing conclusive has ever come up. She was in the South Pacific and never made it to her designated check point. All searches turned up nothing. If you ask me, she was taken by aliens.