From the plaque:
The first United States branch
mint in San Francisco was authorized by Congress July
3, 1852 and opened for operation April 3, 1854. Dr. L.
A. Birdsall was the first superintendent, J. Huston, first
minter, and A. Haraszthy, first assayer.
Tablet placed by California Centennials Commission with the cooperation of the Society of California Pioneers. Dedicated October 31, 1949.