The only time and place in the U.S. where hallmarks were required on silver was in Baltimore during the years 1814 to 1830.

The State Legislature of Maryland passed the Assay Act in early 1814, a law which created the Baltimore Assay Office and required the assay of silver in Baltimore.  The Assay Act also set a quality standard for Baltimore silver, requiring it to be 11 ounces of pure silver in every 12 ounce Troy pound, or 91.7% pure silver.  Any silver made in Baltimore as of August 1, 1814, was required to be assayed and marked by the Assayer, certifying an item’s silver content met the new standard.

The Baltimore coat-of-arms was used as the quality mark.  The quality mark was in the shape of a clip cornered rectangle during the years 1814 to 1823, then an oval shape was used 1824 to 1830.  Date letters were employed indicating the year of assay.  A Head of Liberty mark was also occasionally used; this mark held no governmental purpose but rather was used by some Assayers during their term.

In February, 1830, the Assay Act was changed, no longer requiring the hallmarks of the Assay Office.  In its place, silversmiths were required to mark their own work with quality designations.  Several different numerical markings were employed, designating the silver purity of an item.