1. On May 27, 1937, the Golden Gate Bridge in San Francisco, California, was officially opened to the public. However, many Washington state residents had played significant roles in the bridge's construction, including Seattle engineer Joseph Strauss, who initially proposed the bridge in 1917, and Tacoma-based firm the McClintic-Marshall Company, which helped build it.

2. In 1980, on May 27, Washington's Mount St. Helens erupted in a violent explosion that killed 57 people and caused widespread destruction across the region. The eruption, which had been preceded by weeks of earthquakes and smaller eruptions, remains one of the most significant volcanic events in American history.

3. May 27, 2009, saw the grand opening of Seattle's South Lake Union streetcar, a new public transit option that linked the city's downtown core with the fast-growing South Lake Union neighborhood. The line has since gone through several expansions and renewals, and it is a popular way for locals and tourists to explore the city.

4. On May 27, 1958, the USS Nautilus became the first nuclear-powered submarine to complete a voyage under the North Pole. The historic mission was led by a team of naval officers and technicians, including several who hailed from Washington state. The Nautilus remained in active service until 1980 and is now on display as a museum ship in Connecticut.

5. Finally, on May 27, 1991, Seattle-based software giant Microsoft released its first version of Windows NT, a groundbreaking operating system that introduced several key features still in use today. Windows NT was developed by a team of Microsoft engineers and researchers, many of whom called Washington home. The operating system has since undergone numerous updates and iterations and remains a foundational element of modern computing.