"Washington Territory was created in 1853. It was carved out of the Oregon territory and consisted originally of all of what is now Washington and part of Idaho and Montana. President Franklin Pierce appointed Isaac I. Stevens, first territorial governor and he, upon arrival in the territory, called for elections to the legislative assembly which was to consist of a nine-member Council and an eighteen-member House." -- History of the Washington Legislature, by Don Brazier
On November 11, 1889 President Benjamin Harrison approved the Constitution and issued a proclamation declaring Washington a state. U.S. Secretary of State James Blaine sent a telegram to Miles Moore, the last territorial governor of Washington stating: "The President signed the proclamation declaring Washington to be a state in the Union at 5:00 and twenty-seven minutes this afternoon. "
Thus began the modern political history of the 42nd State of the Union: Washington. Follow the links to further information.