1. On April 21, 1789, John Adams was appointed as the first United States minister to Great Britain.

2. The Washington State Capitol building, located in Olympia, was opened on April 21, 1928. It was designed by architect Joseph Wohleb and is distinguished by its distinctive dome and columns.

3. In 1962, on April 21, Seattle's Century 21 World's Fair opened. This event was held to mark the 50th anniversary of the city's first world's fair, the Alaska-Yukon-Pacific Exposition.

4. On April 21, 1982, Washington State Governor John Spellman signed the Basic Education Act, which outlined the standards and rules for the state's educational system. This act continues to serve as the foundation for the state's current educational system.

5. On April 21, 1856, Seattle was incorporated as a town. The population at that time was around 500 people. Today, Seattle is one of the largest cities in the United States, with a population of over 700,000 residents.