Insignia Description
A Silver metal and enamel device 1 1/8 inches (2.86 cm) in height overall consisting of a shield blazoned: Argent, on a bend Azure three crosses patee Sable fimbriated Argent, in chief the insignia of the 78th Division and in base a mermaid both Proper. Attached below the shield a Blue scroll inscribed "ESSE QUAM VIDERI" in Silver letters.

Symbolism
Blue and white are the colors used for Infantry, the original unit designation. The shoulder sleeve insignia of the 78th Infantry Division represents the Regiment's service with that Division during World War I. The three crosses patee allude to the battle honors awarded the unit for service during World War I - St. Mihiel, Meuse-Argonne and Lorraine. The mermaid is used to indicate Southern New Jersey which is surrounded by beaches and is the place where the unit was organized in 1917.

History
The distinctive unit insignia was originally approved for the 309th Infantry, Organized Reserves on 11 December 1923. It was redesignated for the 309th Regiment, Army Reserve on 30 January 1962.

Source: The US Army Institute of Heraldry