Eastern Oregon is a region of the U.S. state of Oregon. It is not an officially recognized geographic entity; thus, the boundaries of the region vary according to context. It is sometimes understood to include only the eight easternmost counties in the state; in other contexts, it includes the entire area east of the Cascade Range. Cities in the basic eight-county definition include Baker City, Burns, Hermiston, Pendleton, Boardman, John Day, La Grande, and Ontario. Umatilla County is home to the largest population base in Eastern Oregon, accounting for 42% of the region's residents — more than twice that of the region’s second most populous, Malheur County. Hermiston, located in Umatilla County, is the largest city in the region, accounting for 10% of the population. Major industries include transportation/warehousing, timber, agriculture and tourism. The main transportation corridors are I-84, U.S. Route 395, U.S. Route 97, U.S. Route 26, U.S. Route 30, and U.S. Route 20.

Hermiston is a city in Umatilla County, Oregon, United States. Its population of 20,322 makes it the largest city in Eastern Oregon. Hermiston is the largest and fastest-growing city in the Hermiston-Pendleton Micropolitan Statistical Area, the eighth largest Core Based Statistical Area in Oregon with a combined population of 92,261 at the 2020 census. Hermiston sits near the junction of I-82 and I-84, and is 7 miles south of the Columbia River, Lake Wallula, and the McNary Dam. The Hermiston area has become a hub for logistics and data center activity due to the proximity of the I-82 and I-84 interchange, Pacific Northwest fiber optic backbone, and low power costs.