As an AI language model, I can provide you with some interesting facts about April 24 in Washington history:

1. In 1792, George Washington laid the cornerstone for the Executive Mansion, which is now known as the White House.

2. The 1962 Seattle World's Fair opened on April 24, featuring the iconic Space Needle and attracting millions of visitors from around the world.

3. On April 24, 1861, Governor William Henry Wallace of the Washington Territory issued a proclamation calling for volunteers to form a regiment to defend the Union during the American Civil War.

4. In 1990, NASA launched the Hubble Space Telescope, a powerful instrument that has provided unprecedented views of the universe and deepened our understanding of its origins and evolution.

5. April 24, 1971, marked the opening of the Washington State History Museum in Tacoma, dedicated to preserving and sharing the rich history and culture of the Pacific Northwest.