1. On August 31, 1955, the Seattle-Tacoma International Airport officially opened. It was originally named "Seattle-Tacoma International Airport" but was later renamed "Seattle-Tacoma International Airport" in 1961. Today it is considered the largest airport in the Pacific Northwest region and serves over 40 million passengers annually.

2. The world's first commercial electric streetcar made its debut in Seattle on August 31, 1889. The streetcars were used to transport people from different parts of the city and quickly became a popular mode of transportation.

3. August 31, 1927 marked a significant moment in Washington history when Mount St. Helens erupted for the first time in over 100 years. The volcanic explosion caused a massive landslide and caused widespread damage to the surrounding communities. It wasn't until 1980 when the volcano erupted again, resulting in the deadliest volcanic eruption in U.S. history.

4. In 1983, on August 31, the Interstate 90 floating bridge in Seattle was opened to the public as the longest floating bridge in the world. The bridge connects the east and west sides of Lake Washington and spans over 7,500 feet in length.

5. On August 31, 1933, the Grand Coulee Dam project began construction on the Columbia River. The dam was designed to provide hydroelectric power to the Pacific Northwest region and remains one of the largest dams in the world. Today, the Grand Coulee Dam is considered a marvel of engineering and an important landmark in Washington state history.