Oakdale is a city in Stanislaus County, California, United States. It is part of the Modesto Metropolitan Statistical Area. The city was founded in 1871 when the Stockton & Visalia Railroad met the Copperopolis Railroad. The city is located in the east-central portion of the Central Valley, adjacent to the foothills of the Sierra Nevada. California State Routes 108 and 120 (Tioga Pass Road) intersect in the city.