Rodeo is a census-designated place (CDP) located in Contra Costa County, California, in the East Bay sub-region of the San Francisco Bay Area, on the eastern shore of San Pablo Bay, 25 miles northeast of San Francisco. The population was 8,679 at the 2010 census. The town is named for the livestock roundups common in the late 19th century. Cattle from the surrounding hills were regularly driven down through the old town to a loading dock on the shoreline of San Pablo Bay for shipment to slaughterhouses, a practice which continued through the early 20th century. The town of Rodeo is served by the Interstate 80 freeway and State Route 4. The Southern Pacific Railroad main line passes through Rodeo. Rodeo has not been a stop on the railroad since the 1950s.
Rodeo owes much of its history to brothers John and Patrick Tormey, who purchased tracts of land from the Ygnacio Martinez Rancho El Pinole estate in 1865 and 1867.
They became successful ranchers and businessmen, amassed sizable fortunes and held public office. Patrick Tormey (for whom the nearby town of Tormey is named) had visions of this area of Contra Costa County becoming the meatpacking and canning center of the Pacific coast. In partnership with the Union Stockyard Co.