U.S. state flag consisting of a blue field (background) with a buff (light tan) diamond bearing a central coat of arms (arms, coat of) above the inscription “December 7, 1787.”

During the Revolutionary War (1775–83) distinctive colours were carried by troops from Delaware, but an official state flag was not adopted until July 24, 1913. The original symbolism of the diamond shape is unknown, but it may have been chosen simply as a distinctive design. The choice of colours is clearly understood: the uniforms of Continental Army troops were blue with buff facings. Precise colour shades have been specified for Delaware's “colonial” blue and buff, but the latter is often misrepresented as yellow.

The date along the bottom of the flag is when Delaware became the first state to ratify the U.S. Constitution (Constitution of the United States of America). The coat of arms, which also appears in the state seal, was approved in 1777. It incorporates symbols appropriate for the late 18th century—a soldier, a farmer, agricultural produce (a sheaf of wheat and an ear of corn), an ox, and a ship. The design is completed by the state motto, “Liberty and independence.”