The first recorded European landing on the Washington coast was by Spanish Captain Don Bruno de Heceta in 1775. He claimed the coastal lands up to Prince William Sound for Spain as part of their claimed rights under the Treaty of Tordesillas, which they maintained made the Pacific a “Spanish lake” and all its shores part of the Spanish Empire.
The British-Spanish Nootka Convention of 1790 ended Spanish claims of exclusivity and opened the Northwest Coast to explorers and traders from other nations. American captain Robert Gray. He named the river after his ship, the Columbia. The Lewis and Clark Expedition entered the state on October 10, 1805.
In 1836, a group of missionaries, including Marcus Whitman, established several missions and Whitman’s own settlement Waiilatpu, in what is now southeastern Washington state, near present day Walla Walla County, in territory of both the Cayuse and the Nez Perce Indian tribes. Whitman’s settlement would in 1843 help the Oregon Trail, the overland emigration route to the west, get established for thousands of emigrants in following decades.
The growing populace of Oregon Territory north of the Columbia River formally requested a new territory, which was granted by the U.S. government in 1853. The boundary of Washington Territory initially extended farther east than the present state’s, including what is now the Idaho Panhandle and parts of western Montana, and picked up more land to the southeast that was left behind when Oregon was admitted as a state. The creation of Idaho Territory in 1863 established the final eastern border. Washington became the 42nd state in the United States on November 11, 1889.