The first European record of a landing on the Washington coast was by Spanish Captain Don Bruno de Heceta in 1775, on board the Santiago, part of a two-ship flotilla with the Sonora. They claimed all the coastal lands up to the Russian possessions in the north for Spain.

In 1778, British explorer Captain James Cook sighted Cape Flattery, at the entrance to the Strait of Juan de Fuca, but the straits would not be explored until 1789, by Captain Charles W. Barkley. Further explorations of the straits were performed by Spanish explorers Manuel Quimper in 1790 and Francisco de Eliza in 1791, then by British Captain George Vancouver in 1792.

During the Great Depression, a series of hydroelectric dams were constructed along the Columbia river as part of a project to increase the production of electricity. This culminated in 1941 with the completion of the Grand Coulee Dam, the largest dam in the United States.

During World War II, the Puget Sound area became a focus for war industries, with the Boeing Company producing many of the nation's heavy bombers and ports in Seattle, Bremerton, and Tacoma were available for the manufacture of warships. Seattle was the point of departure for many soldiers in the Pacific, a number of which were quartered at Golden Gardens Park. In eastern Washington, the Hanford Works atomic energy plant was opened in 1943 and played a major role in the construction of the nation's atomic bombs.

On May 18, 1980, following a period of heavy tremors and eruptions, the northeast face of Mount St. Helens exploded outward, destroying a large part of the top of the volcano. This eruption flattened the forests, killed 57 people, flooded the Columbia River and its tributaries with ash and mud, and blanketed large parts of Washington in ash, making day look like night.

Washington's executive branch is headed by a governor elected for a four-year term. The current governor of Washington is Christine Gregoire, a Democrat. She has been governor since 2005.

The Washington Supreme Court is the highest court in the judiciary of the state of Washington. Nine justices serve on the bench, and are elected at large.

Significant business within the state include the design and manufacture of jet aircraft (Boeing), computer software development (Microsoft, Amazon.com, Nintendo of America), electronics, biotechnology, aluminum production, lumber and wood products, mining, and tourism.

The state has significant amounts of hydroelectric power generation. Significant amounts of trade with Asia pass through the ports of the Puget Sound. See list of United States companies by state. The state of Washington is one of only seven states that does not levy a personal income tax. Neither does the state collect a corporate income tax. However, Washington businesses are responsible for various other state levies. Washington's state sales tax is 6.5 percent, and it applies to services as well as products.[1] Most foods are exempt from sales tax; however, prepared foods, dietary supplements and soft drinks remain taxable. The combined state and local retail sales tax rates increase the taxes paid by consumers, depending on the variable local sales tax rates, generally between 8 and 9 percent[2]. An excise tax applies to certain select products such as gasoline, cigarettes, and alcoholic beverages. Property tax was the first tax levied in the state of Washington and its collection accounts for about 30 percent of Washington's total state and local revenue. It continues to be the most important revenue source for public schools, fire protection, library, park and recreation, and other special purpose districts.

Bill Gates (worth $73 billion) is the best known billionaire from the state, and wealthiest man in the world. Other Washington state billionaires Paul Allen, (Microsoft), Steve Ballmer (Microsoft), Jeffrey Bezos (Amazon), Craig McCaw (McCaw Cellular), James Jannard (Oakley), John Edson (leisure craft), Howard Schultz (Starbucks) and Charles Simonyi (Microsoft).