1. The first Earth Day observance was held on April 20, 1970, in Oregon. It was attended by thousands of people who rallied in Portland and Eugene to raise awareness about environmental issues.

2. On April 20, 1999, two students opened fire at Columbine High School in Colorado. The tragedy prompted Oregon to pass new gun laws, including a requirement for background checks on all gun sales.

3. April 20, 1859, marked the founding of the Oregon State Agricultural Society, which later became the Oregon State Fair. The fair has been held annually ever since, showcasing the state's agriculture, arts, and culture.

4. In 1994, on April 20, Oregon became the first state to legalize physician-assisted suicide. The law allows terminally ill patients to request medication to end their lives, under certain conditions.

5. April 20, 1986, was the day of the worst nuclear accident in US history, when the Chernobyl nuclear power plant in Ukraine exploded. The event had far-reaching effects, including increased scrutiny of nuclear power plants in Oregon and around the world.