1. In 1790, President George Washington signed into law a bill establishing the District of Columbia as the capital of the United States. The new federal district was carved from land ceded by Maryland and Virginia.

2. On April 10, 1865, Confederate General Robert E. Lee surrendered his army to Union General Ulysses S. Grant at Appomattox Court House in Virginia, effectively ending the American Civil War.

3. The Seattle World's Fair, also known as the Century 21 Exposition, opened on April 10, 1962. The six-month-long event showcased technological innovations and cultural displays from around the world and drew over 10 million visitors.

4. In 1972, a massive eruption of the Mount St. Helens volcano in southwestern Washington caused widespread destruction and killed 57 people. The eruption, which had a force equivalent to 500 atomic bombs, was one of the most powerful volcanic events in U.S. history.

5. On April 10, 1980, the State Route 99 Alaskan Way Viaduct, a double-decker freeway running along the Seattle waterfront, was opened to traffic. The viaduct served as a major transportation route in the city for over 60 years until it was closed in 2019 due to safety concerns and subsequently demolished.