Delaware's flag makes its argument with a date. Below the buff diamond on its colonial blue field, in plain white characters, is December 7, 1787: the day Delaware's convention ratified the United States Constitution, before any other state had voted. Everything else on the flag is older still. The coat of arms inside the diamond was adopted in 1777, and the blue and buff around it are the colors of George Washington's uniform. For a small state, it is a flag unusually preoccupied with being first.
Washington's colors
The field is "colonial blue" and the diamond is buff, and the pairing is deliberate. Blue coats faced with buff were the uniform of General Washington and his officers in the Continental Army, and Delaware's three Revolutionary counties sent troops who fought through most of the war's major campaigns. When the state finally got around to adopting a flag in 1913, the commission reached back to that palette.
For four decades the exact shades were left to flag makers' judgment, which produced predictable drift. In 1954 the state settled the matter, matching colonial blue and buff to numbered standards of the Textile Color Card Association ("arno blue" and "golden beige" respectively), with the National Bureau of Standards verifying the match that November. Delaware is one of the few states to have gone to a federal standards laboratory over the color of its flag.
A coat of arms older than the Constitution
The arms inside the diamond were adopted in 1777, which makes them a decade older than the date printed beneath them. The shield is divided into three horizontal bands carrying a sheaf of wheat, an ear of corn, and an ox standing on grass: agriculture, three ways. Above the shield rides a sailing ship, for the shipbuilding and coastal trade that sustained the colony along the Delaware River and Bay.
The supporters are a matched pair. On the left, a farmer in a red shirt holds a hoe. On the right stands a militiaman with a musket. Farm and militia, livelihood and defense. Below them a ribbon reads "Liberty and Independence," the state motto. The same arms appear on the state seal, so Delaware's flag is in one sense another seal-on-a-bedsheet design, but the diamond and the two-color scheme give it more structure than most of the genre.
The diamond
Why a diamond? The 1913 statute does not say, and no record of the commission's reasoning survives. It may have been nothing more than a handsome way to frame the arms. It does, however, rhyme with one of Delaware's nicknames, "The Diamond State." Tradition credits that name to Thomas Jefferson, who is said to have called Delaware a jewel among the states because of its strategic position on the Atlantic seaboard. No one has ever produced the quote, and it is best treated as legend, but the nickname was in circulation long before 1913 and the flag's centerpiece has reinforced it ever since.
December 7, 1787
The date is the flag's whole point. In the fall of 1787, the proposed federal Constitution went out to the states, and Delaware moved fastest. Its ratifying convention of thirty delegates met in Dover and on December 7 approved the document unanimously, 30 to 0. Pennsylvania followed five days later; Rhode Island, the last holdout, took until 1790. Being first earned Delaware the nickname "The First State" and, by tradition, the first position in presidential inauguration parades and other national processions where states appear in order of ratification.
Putting the date on the flag in 1913 turned a piece of trivia into standing civic identity. Delaware is one of only a handful of states to print a full calendar date on its flag, and the only one whose date marks a ratification rather than an independence or a battle.
Adoption and afterlife
Delaware fought the Civil War as a slave state that stayed in the Union, and its regiments carried blue flags bearing the state arms with regimental names below. Those colors are the flag's direct ancestors. In February 1913 the General Assembly authorized a commission to design an official state flag, and its recommendation, the arms in a buff diamond on colonial blue with the ratification date below, became law on July 24, 1913. The design is now codified at Title 29, Section 306 of the Delaware Code, and it has never been altered, apart from the 1954 color standardization.
Its critical reputation is middling. In the North American Vexillological Association's 2001 survey of state and provincial flag designs, Delaware placed 52nd out of 72, dragged down by the same complaint that dogs most American state flags: detailed heraldry that cannot be read at a distance. The counterargument is that the diamond, the two-tone field, and the date make it recognizably Delaware's in a way that a dozen seal-on-blue flags are not. At the statehouse in Dover it flies below the national flag, buff diamond out, date legible to anyone who walks close enough.
References
[1] Delaware Code, Title 29, § 306 (state flag). https://delcode.delaware.gov/title29/c003/index.html
[2] State of Delaware, "Delaware Facts and Symbols: State Flag." https://delaware.gov/guides/facts/
[3] "Flag of Delaware," Wikipedia. https://en.wikipedia.org/wiki/Flag_of_Delaware
[4] Whitney Smith, "Flag of Delaware," Encyclopaedia Britannica. https://www.britannica.com/topic/flag-of-Delaware
[5] North American Vexillological Association, "2001 State and Provincial Flag Survey." https://nava.org/digital-library/design/surveys/
[6] State Symbols USA, "Delaware State Flag." https://statesymbolsusa.org/symbol-official-item/delaware/state-flag/flag-delaware