A Silver color metal and enamel device 1 1/4 inches (3.18 cm) in height consisting of a shield blazoned: Azure, a closet between two wavy barrulets, surmounted by a pairle, Argent; overall the old insignia of the First Regiment of Infantry, Illinois National Guard, (wheel within a diamond) Proper; in chief four fleurs-de-lis, three and one, of the second. Attached above the shield on a wreath, upon a grassy field the blockhouse of old Fort Dearborn, all Silver Gray. Attached below and to the sides of the shield a Silver scroll inscribed "DUCIT AMOR PATRIAE" in Blue letters.
The shield is blue the present Infantry color, and the main charges are silver or white the old Infantry facing color. The pairle is taken from the Chicago seal: the first wavy barrulets represents Spanish-American War service, the closet Mexican Border duty, and the second wavy barrulets the second time the organization was in Federal service overseas. The four fleurs-de-lis represent the engagements during World War I. The charge in the fess point is the insignia of the old First Regiment of Infantry, Illinois National Guard. The motto translates to "Led By Love Of Country."
The distinctive unit insignia was approved for the 131st Infantry Regiment on 19 April 1927.