1450 CE - Estimated date for the landslide that created the
Bridge of the Gods which temporarily dammed the Columbia River where
Bonneville Dam now stands.
1700 - January 26: An
earthquake with an estimated
moment magnitude of 8.7–9.2 strikes the region, causing damage to native settlements and sending a tsunami across the Pacific.
George Vancouverexplores and names the
Puget Sound. During this expedition, he also sighted and named several Cascade volcanoes and other geographic features.
1818: October 20 - The
Treaty of 1818 is signed, allowing for joint occupation of
Oregon Country (which included present day Washington) by the United Kingdom and United States.
1819: February 22 - The
Adams-Onis Treaty is signed between the United States and Spain, which includes Spain withdrawing its claim to the Pacific Northwest.
1821: The North West Company merges with the
Hudson's Bay Company with the latter becoming the British authority in what is now Washington.
1824:
Fort Vancouver in the present day Washington city of the same name becomes the Hudson's Bay Company's Columbia District headquarters.
1843
Champoeg, a settlement in the
Willamette Valley becomes the American capital of Oregon Country, which Washington was a part of at the time.
Hudson's Bay Company moves their Columbia District headquarters to
Fort Victoria in the present day
British Columbia city of the same name.
Oregon City becomes the American capital of Oregon Country.
1846 - June 15: The
Oregon Treaty between the United Kingdom and United States is signed, setting the boundary between the two nations occupying Oregon Country at the
49th parallel and placing present day Washington in
Oregon Territory.
1855: June 9: Treaties between the United States and several Eastern Washington Native American tribes are signed at the
Walla Walla Council.
1855–1856: The
Puget Sound War is fought between the United States and several Native American tribes in the Puget Sound Region.
1855–1858: The
Yakima War is fought between the United States and several Native American tribes in Central Washington.
1858: The
Coeur d'Alene War is fought between the United States and several Native American tribes in Eastern Washington and the Idaho Panhandle.
1859
February 14:
Oregon is granted statehood with its present boundaries. The remaining portion of the territory to the east of the present state is added to Washington Territory.
June 15: An American settler on
San Juan Islandkills a pig owned by a British colonist, initiating military occupation of the island by both nations while peaceful negotiations between both nations determine the formal international boundary.
1951 - June 1:
Washington State Ferries, a state run ferry service in the
Puget Sound and
Salish Sea is established. Prior to this, ferries in the region had been operated by private companies.
1960 - Seattle becomes the first city in the state to exceed 500,000 people.
1961 - December 8: The
Space Needle opens in Seattle.
October 12: The
Columbus Day Storm of 1962 (which was a remnant of Typhoon Freda) strikes the Pacific Northwest, producing wind gusts up to 100 mph (160 km/h) in the
Tacoma area.
2001 - February 28: A
Mw6.8 earthquake centered 57 kilometres (35 mi) below the Puget Sound between Olympia and Seattle strikes the Puget Sound region.
2004 - October 1:
Mount St. Helenserupts. Eruptive activity would last until January 2008.
2006 - December 14–15: The
Hanukkah Eve storm produces hurricane-force winds and cuts power to 1.2 million customers across the state.
2012 - December 6: Washington becomes the
first state to legalize recreational use of
cannabis.
2020 - January 21: Washington reports the United States' first case of
COVID-19. Washington would record the nation's first death from the disease the following month.
2021 - June & July: The
2021 Western North America heat wave kills 91 people in Washington, making it the state's second deadliest natural disaster on record.[26]
^Hicks, Brent A. (2004). Marmes Rockshelter: A Final Report on 11,000 Years of Cultural Use, Pullman, Washington: Washington State University Press,
ISBN0-87422-275-3.
^Stafford, Thomas W. (2014). "Chronology of the Kennewick Man skeleton (chapter 5)". In Douglas W. Owsley; Richard L. Jantz (eds.). Kennewick Man, The Scientific Investigation of an Ancient American Skeleton. Texas A&M University Press.
ISBN978-1-62349-200-7.