The firehouse went through several building stages; the engine bays were built in 1943, the front office was built in 1948, and the rear sleeping quarters were built in 1962.  Originally known as the Alvarado Fire Station, after incorporation, it became Station #2 for Union City (Station #1 was the Decoto Fire Station).

The corps of firefighters assigned to this station were an "all vonunteer" company until 1964.  During that period, the Fire Chief (Mr. Elvin Rose) lived approximately one block away from the station, where he lives to this day.  To contact the Fire Department, a citizen would call the number assigned to the firehouse, which would ring at the Chief's house.  The Chief would then push a button to activate the siren on the rooftop of the firehouse, thus summoning the volunteer firefighters.  Another method existed that the citizens could use; a button located on the front of the firehouse could be pushed to activate the siren.

In 1964, Union City had enough firefighters to assure that the Alvarado Station was manned full time by city staff, and the volunteer department was disbanded. 

The firehouse closed in 1984, and remained empty for several years, until a Union City Police officer rented it from the city to use as his residence for a few years.  When the officer moved away from Union City, the building remained empty until the Historical Museum occupied it in 2001.