|State||Nevada and Oregon|
|County||Humboldt and Harney|
|• Total||16.1 sq mi (41.7 km2)|
|• Land||16.1 sq mi (41.7 km2)|
|• Water||0 sq mi (0 km2)|
|Elevation||4,207 ft (1,282 m)|
|• Density||2.9/sq mi (1.1/km2)|
|Time zone||Pacific (PST) (UTC-8)|
|• Summer (DST)||PDT (UTC-7)|
|GNIS feature ID||845425|
Denio is a census-designated place (CDP) that lies on the Nevada-Oregon state line in Humboldt County, Nevada, in the United States. There was formerly a Denio post office north of the state line in Harney County, Oregon. The population of the CDP, which is entirely in Nevada, was 47 at the 2010 census; additional development considered to be Denio extends into Oregon. The CDP includes a post office, a community center, a library, and the Diamond Inn Bar, the center of the town's social life. Recreational activities available in the Denio area include fishing, opal mining, rockhounding, hunting, and visiting the hot springs. The Humboldt County School District operates the Denio School, a kindergarten-eighth grade (K-8) school, on the Nevada side of the state line.
Denio Junction is about two miles (3 km) south of Denio, at the junction of State Route 140 and State Route 292. Denio Junction's motel provides gasoline (although not reliably), food, groceries, and lodging. Air transportation is available via the Denio Junction Airport, a two-runway graded airstrip. There is no scheduled air or ground transportation serving this field, which is a short walk from any part of Denio Junction.
Denio was named for Aaron Denio, who settled in the area in 1885. Aaron Denio was born in 1824 in Illinois and traveled to California in 1860. He worked in milling, mining, and farming in Nevada and California for 25 years before settling near the Oregon-Nevada border. He died at Denio in 1907. Denio post office was established in Oregon in 1888. After World War II a number of businesses relocated south of the state line to take advantage of Nevada's more liberal liquor and gambling laws. The post office moved and reopened in Nevada in 1950.
- "Denio". Geographic Names Information System. United States Geological Survey. December 12, 1980. Retrieved March 27, 2012.
- "Denio Post Office (historical)". Geographic Names Information System. United States Geological Survey. August 1, 1994. Retrieved March 27, 2012.
- "Geographic Identifiers: 2010 Demographic Profile Data (G001): Denio CDP, Nevada". U.S. Census Bureau, American Factfinder. Retrieved January 24, 2013.
- "Denio, Nevada". travelNevada.com. Nevada Commission on Tourism. Retrieved March 27, 2012.
- "Denio Junction". Geographic Names Information System. United States Geological Survey. December 12, 1980. Retrieved March 27, 2012.
- McArthur, Lewis A.; McArthur, Lewis L. (2003) . Oregon Geographic Names (7th ed.). Portland, Oregon: Oregon Historical Society Press. p. 278. ISBN 978-0875952772.
- Kirchmeier, Mark (June 16, 1979). "Denio never scared Reno, Vegas". The Oregonian.