The Eastern Oregon Desert is a large, poorly defined region in Eastern Oregon notable for its lack of precipitation. In fact, the term is somewhat redundant, since all of Eastern Oregon could be considered a desert. The region is geologically diverse, since it includes the Great Basin Desert in the south, the Columbia River Basalts, and also large sections of much older mountain ranges that accumulated as terranes. It is also demographically diverse, with some areas being relatively populous, driven by farming or tourism, while other parts of it are very empty. It also is not, strictly speaking, confined to Oregon, since there is an arid area between mountain ranges that runs from British Columbia to Nevada. However, the Oregon section is unique from areas both further south or north.
What all of the desert has in common is that it is in a rain shadow caused by the volcanic Cascade Range. This makes the area much more dry than Western Oregon (which is not saying much), although whether most or all of it counts as a desert depends on definitions. If we take this as a guideline, most of Oregon would be considered arid or semi-arid, since rainfall runs between 5 and 20 inches a year. Of course, in such a large area, there are large variations, especially because there are mountain ranges, such as the Blue Mountains that collect rain and snowfall and provide a source of water for the surrounding land. Settlements in the area tend to be along the river systems, such as the Deschutes and John Day, that gather water from mountain ranges. Another key point in the areas lack of aridity is the the fact that winter temperatures are very continental, meaning that for at least four months a year, water loss through evaportation is not the issue it would be in deserts located further south. Because of that, the desert usually takes the form of a steppe, with juniper trees and sage brush covering the ground.
Most of the population of the area is concentrated in a few places, such as the resort town of Bend, or along the Columbia River, where wheat is farmed. The area to the southeast is very isolated and sparsely populated, much like neighboring Nevada. For example, the three southeastern counties have an area about the size of Austria, but have a population of about 46,000 people.
I mention this desert for several reasons. One is to let people know that Oregon isn't solid rainforest, but is actually predominantly arid. In general, the Western States of the United States is full of climatic variation. The other reason, and one that I can't quite capture, is that I really appreciate the area. I haven't had a chance to drive over the mountains in some years, but the endless miles of basalt and juniper are inspiring, as is the green, pleasant little valleys that move between them.