1. On April 18, 1906, a devastating earthquake struck San Francisco, California, causing widespread destruction and loss of life. Although Washington was not directly affected by the earthquake, many residents of the state were involved in relief efforts to help the survivors.

2. On April 18, 1942, the famous Doolittle Raid took place, in which a group of American pilots flew bombing missions over Tokyo during World War II. One of the pilots involved in this mission was from Washington, and the state played a significant role in training and supplying the crews for the raid.

3. On April 18, 1974, a major explosion occurred at the Olympic Pipeline near Whatcom, Washington, causing a significant amount of damage and resulting in the deaths of three workers. This incident led to increased safety regulations and scrutiny for the oil and gas industry in the state.

4. On April 18, 1980, the infamous eruption of Mount St. Helens occurred in southwestern Washington, causing widespread devastation and loss of life. The eruption remains one of the most significant natural disasters in the state's history.

5. On April 18, 2020, protests and demonstrations took place in downtown Olympia, Washington, in response to the state's coronavirus lockdown measures. The protests, which were attended by several hundred people, sparked a wider discussion about the balance between public safety and individual freedoms during the pandemic.