1. In 1867, the Washington Territorial Legislature met for the first time in Olympia, the capital city of Washington. This marked a significant milestone in the development of Washington State, as the legislature was responsible for passing laws and creating a framework for the future government of the state.

2. On November 15, 1889, Washington was admitted to the Union as the 42nd state. This day is celebrated as Washington Statehood Day, and marks the anniversary of the state's admission into the Union. The decision to admit Washington was made after many years of lobbying by local leaders, who argued that the territory was ready for statehood.

3. In 1935, the Hoover Dam was officially dedicated by President Franklin D. Roosevelt. Although the dam is located in Nevada, it provides electricity to Washington and several other states in the western United States. The dam is considered one of the greatest engineering achievements of the 20th century, and is a major source of hydroelectric power in the region.

4. On November 15, 1969, the first Vashon Island coffeehouse was opened. This coffeehouse, which was called The Usual, quickly became a popular gathering spot for local artists and musicians. The Usual played an important role in the development of Vashon Island's arts community, and helped to establish the island as a center for alternative culture in the region.

5. In 2006, Seattle was named the seventh most environmentally friendly city in the United States by Popular Science magazine. The ranking was based on a variety of factors, including the city's green building policies, its use of renewable energy sources, and its public transportation system. Seattle has continued to be a leader in environmental sustainability, and is now known as one of the most eco-friendly cities in the world.