In the 1940s, the city allowed the State of Oregon to use it as an annex to an armory built at that time and located just to the east.

[9] In 1963, the building was turned into the first Columbia River Maritime Museum, which opened in August of that year.

[2] The building was added to the National Register of Historic Places in 1984, as Astoria City Hall.

[12] In 1980, members of the Clatsop County Historical Society voted to purchase the Old City Hall and renovate it for use as a museum.

[13][14] Interior renovation and exterior restoration were carried out in 1987–88, funded by private grants and donations.