Upper Green Valley is a valley in the Cuyamaca Mountains in San Diego County, California.
Its mouth lies at an elevation of 4,163 feet / 1,269 meters.
[1] The Sweetwater River has its source at the top of Upper Green Valley.
[2] Upper Green Valley was a part of a pathway between the California coast in the vicinity of San Diego and the Colorado River.
As part of the San Antonio–San Diego Mail Line, mules carried passengers 18 miles up and down Upper Green Valley, Oriflamme Canyon, Vallecito Wash, Vallecito Creek and Carrizo Creek between Lassiter's Ranch and Carrizo Creek Station.