Settlers met at Cowlitz Landing and discussed the establishment of a new territory north of the Columbia River
On July 4, 1851 John Chapman delivered a speech in Olympia calling for a convention to discuss creating a new territory north of the Columbia. The primary reason for establishing the new territory was that the distance to the capital of Oregon Territory (Oregon City) was too far away to represent the citizens in what is now Washington. On August 29, 1851 the settlers met at Cowlitz Landing where they discussed drafting a constitution.
A year later on November 25, 1852, the settlers met again at Monticello (present-day Longview, Washington) and drafted a memorial to Congress asking for the establishment of a new territory north of the Columbia River, to be named "Columbia Territory." Oregon Territorial Governor Joseph Lane and the Oregon Territorial Legislature supported the memorial and forwarded it to Congress.
On March 2, 1853 Congress passed the bill creating the new territory, but they changed the name to Washington to honor the "Father of the Country," George Washington. The law was known as the Organic Act and served as the basis for law in Washington until Washington became a state in 1889.
At the time it was established, Washington Territory extended east to the Rocky Mountains, and included all of present-day Washington, western Idaho and western Montana.