The following important events in the history of Washington affected political boundaries, record-keeping, and family movements.
1800s: At the beginning of the nineteenth century, Spain, Russia, and England all claimed what is now Washington.
1811: John Jacob Astor's American Fur Company established a trading post at Fort George (Astoria). This was the first settlement in this area.
1819: Spain withdrew her claims.
1825: Russia withdrew her claims.
1836: Marcus Whitman established the second white settlement near present-day Walla Walla. Early settlement centered in the Willamette valley.
1846: The present boundary between the United States and Canada was established.
1848: The Oregon Territory was created. It included what is now Oregon, Washington, Idaho, and parts of Montana and Wyoming.
1849: Settlers went farther north into the Puget Sound area to obtain food and lumber that was needed in the California gold fields.
1850: The Oregon Donation Act was passed. This guaranteed land to those who settled and cultivated land in the territory before 1855. This attracted an estimated 30,000 new settlers.
1853: Treaty at Lapwai asked Nez Perce to adjust the border of their reservation.
1853: (March 2,)Washington Territory was created from the northern part of Oregon Territory.
1858: The Coeur d"Alene, Spokane tribes united with the Palouse and Yakima tribes to fight U.S. forces near Rosalia, Washington. 1859 the tribes were forced to surrender.
1859: Oregon became a state. Washington Territory was enlarged to include the remaining Oregon territory not included in the new state.
1860: The discovery of gold near Walla Walla attracted many prospectors.
1863: The Idaho Territory was created from lands in eastern Washington Territory.
1873: U.S. President Grant executive order gave back northern 1/2 of land to Chief Joseph. 1875 Executive order rescinded.
1877: Chief Joseph given 30 days to move his tribe.
1878: Bannock War fight for their fields of Camas
1881: The Northern Pacific Railway reached Spokane.
1888: The transcontinental railroads reached Washington and brought a great influx of settlers.
1889: (November 11,) Washington became a state. Seattle was the largest city and the chief supply point for the gold rush to the Yukon territory in Alaska.
1898: Over 300,000 men were involved in the Spanish-American War which was fought mainly in Cuba and the Philippines.
1917–1918: More than 26 million men from the United States ages 18 through 45 registered with the Selective Service. World War I over 4.7 million American men and women served during the war.
1930's: The Great Depression closed many factories and mills. Many small farms were abandoned, and many families moved to cities.
1950–1953: Over 5.7 million American men and women served in the Korean War.
1950's–1960's The building of interstate highways made it easier for people to move long distances.
1964–1972: Over 8.7 million American men and women served in the Vietnam War
Histories are great sources of genealogical information. Many contain biographical information about individuals who lived in the area, including:
Some of the most valuable sources for family history research are local histories. Published histories of towns, counties, and states usually contain accounts of families. They describe the settlement of the area and the founding of churches, schools, and businesses. You can also find lists of pioneers, soldiers, and civil officials. Even if your ancestor is not listed, information on other relatives may be included that will provide important clues for locating your ancestor. A local history may also suggest other records to search. Local histories are extensively collected by the Family History Library, public and university libraries, and state and local historical societies. The United States Research "History" page cites nationwide bibliographies of local histories which include histories of Washington.
- The Evolution of Washington Counties. 
State Histories Useful to Genealogists
Good genealogists strive to understand the life and times of their ancestors. In this sense, any history is useful. But certain kinds of state, county, and local histories, especially older histories published between 1845 and 1945, often include biographical sketches of prominent individuals. The sketches usually tend toward the laudatory, but may include some genealogical details. If these histories are indexed or alphabetical, check for an ancestor's name. Some examples for the State of Washington are:
- An Illustrated History of the State of Washington: Containing . . . Biographical Mention of . . . its Pioneers and Prominent Citizens . 
United States History
The following are only a few of the many sources that are available:
- The Almanac of American History,   This provides brief historical essays and chronological descriptions of thousands of key events in United States history.
- Dictionary of American History, Revised ed   This includes historical sketches on various topics in U.S. history, such as wars, people, laws, and organizations. A snippet view is available at Google books.
- Webster's Guide to American History: A Chronological, Geographical, and Biographical Survey and Compendium    This includes a history, some maps, tables, and other historical information.
To find more books and articles about Washington 's history use the Internet Google search for phases like "Washington history." Family History Library Catalog Surname Search lists many more histories under topics like:
- WASHINGTON - HISTORY
- WASHINGTON, [COUNTY] - HISTORY
- WASHINGTON, [COUNTY], [TOWN] - HISTORY
- WASHINGTON, BIBLIOGRAPHY
- Abbott, Newton Carl and Fred E. Carver. The Evolution of Washington Counties. N.p.: Yakima Valley Genealogical Society & Klickitat County Historical Society, Washington,1978. (Family History Library book 979.7 D25a; fiche 6051194.) This is listed in the Family History Library Catalog under WASHINGTON - HANDBOOKS, MANUALS, ETC.
- Filby, P. William. A Bibliography of American County Histories. Baltimore: Genealogical Publishing, 1985. (FHL book 973 H23bi)
- Kaminkow, Marion J. United States Local Histories in the Library of Congress. 5 vols. Baltimore: Magna Charta Book, 1975-76. (FHL book 973 A3ka.)
- Hines, Harvey K. An Illustrated History of the State of Washington: Containing . . . Biographical Mention of . . . its Pioneers and Prominent Citizens . . . Chicago, Illinois: Lewis Pub. Company, 1893. (Family History Library book 979.7 D3h; film 1000637.)
- Schlesinger, Jr., Arthur M. The Almanac of American History. Greenwich, Conn.: Bison Books, 1983. (FHL book 973 H2alm)
- Dictionary of American History, Revised ed., 8 vols. New York: Charles Scribner's Sons, 1976. (FHL book 973 H2ad.)
- Webster's Guide to American History: A Chronological, Geographical, and Biographical Survey and Compendium. Springfield, Mass.: G&C Merriam, 1971. (FHL book 973 H2v)
- Limited view at Google Books
- Writings on American History By American Historical Association, Library of Congress, United States National Historical Publications Commission, Published by KTO Press, 1921 FHL book 973 H23w