Oregon is a state in the Pacific Northwest region of the United States. Oregon borders the Pacific Ocean on the west, Washington on the north, Idaho on the east, and California and Nevada on the south. The Columbia and Snake Rivers form, respectively, much of its northern and eastern borders. Between two north-south mountain ranges in western Oregon—the Pacific Coast Range and the Cascade Mountain Range—lies the Willamette Valley, the most densely populated and agriculturally productive region of the state.
Oregon has one of the most diverse landscapes of any state in the U.S. It is well known for its tall, dense forests; its accessible, scenic Pacific coastline; and its rugged, glaciated Cascade volcanoes. Other areas include semiarid scrublands, prairies, and deserts that cover approximately half the state in eastern and north-central Oregon.
Oregon's population in 2000 was 3,421,399, a 20.4% increase over 1990. The Census Bureau estimated Oregon's population to have reached 3,700,758 by 2006. Residents are called "Oregonians" (pronounced or-i-GO-nee-inz).