Livermore is a city in Alameda County, California. With a 2020 population of 87,955, Livermore is the most populous city in the Tri-Valley, givin…Livermore is a city in Alameda County, California. With a 2020 population of 87,955, Livermore is the most populous city in the Tri-Valley, giving its name to the Livermore Valley. It is located on the eastern edge of California's San Francisco Bay Area, making it the easternmost city in the area.