The Maryland flag has been described as the perfect state flag--bold colors, interesting patterns, and correct heraldry--a flag that fairly shouts "Maryland." The design of the flag comes from the shield in the coat of arms of the Calvert family, the colonial proprietors of Maryland. George Calvert, first Lord Baltimore, adopted a coat of arms that included a shield with alternating quadrants featuring the yellow-and-black colors of his paternal family and the red-and-white colors of his maternal family, the Crosslands. When the General Assembly in 1904 adopted a banner of this design as the state flag, a link was forged between modern-day Maryland and the very earliest chapter of the proprietorship of the Calvert family.

Despite the antiquity of its design, the Maryland flag is of post-Civil War origin. Throughout the colonial period, only the yellow-and-black Calvert family colors are mentioned in descriptions of the Maryland flag. After independence, the use of the Calvert family colors was discontinued. Various banners were used to represent the state, although none was adopted officially as a state flag. By the Civil War, the most common Maryland flag design probably consisted of the great seal of the state on a blue background. These blue banners were flown at least until the late 1890s.