1. Earth Day was founded on April 22, 1970, in Washington, D.C. by US Senator Gaylord Nelson to promote environmental awareness and protection. The first Earth Day attracted millions of people in the United States and led to the creation of the Environmental Protection Agency and the passage of several landmark environmental laws.

2. On April 22, 1864, President Abraham Lincoln signed the Yosemite Grant, which set aside over 39,000 acres of land in California for public use, becoming the first time such an action was taken.

3. In 1971, the Washington, D.C. baseball team, the Senators, played its last home opener on April 22. The team left D.C. for Texas the following year, making the area without a baseball team until the arrival of the Washington Nationals in 2005.

4. On April 22, 1994, United States Immigration and Customs Enforcement agents discovered 59 Chinese immigrants locked inside a shipping container in Washington State. The investigation led to the arrest of 13 people involved in a human smuggling operation.

5. On April 22, 1909, the second international conference on the standardization of electrical units was held in Washington, D.C. The conference led to the creation of the International Electrotechnical Commission, an organization that promotes international standards for electrical and electronic technologies.