Belfast Beverages was a SF-based beverage company with a bottling plant at 3521 Chestnut St. near the California Hotel c.1939 to c.1958. The company is noted for creating Belfast Old Fashion Mug Root Beer, which today is known as Mug Root Beer. The company has been around since 1877, and is part of Pepsi. 1
The year the plant opened is unknown, but the address is mentioned in a 1939 ad, 2 and the company sponsored an Oakland bowling team in 1938. 3
Likewise the exact year the plant closed is unknown. In 1957, the company acquired the former Oakland Oaks ballpark in Emeryville and demolished it to build a new plant. Work began in May 1958, noting that the company was "forced to abandon its present plant at 36th and Chestnut to make way for a new freeway." 4 It's unknown when the new plant was completed and the Chestnut St. plant closed.
There is a "ghost sign" on San Leandro St. near 34th Avenue for Belfast Old Fashioned Mug Root Beer, copyright 1950. 5