Flags of the U.S. states and territories

The flags of the U.S. states, territories, and the District of Columbia (Washington, D.C.) exhibit a variety of regional influences and local histories, as well as different styles and design principles. Modern U.S. state flags date from the turn of the 20th century, when states considered distinctive symbols for the 1893 World's Columbian Exposition in Chicago, Illinois. Most U.S. state flags were designed and adopted between 1893 and World War I.

The most recently adopted state flag is that of Minnesota, adopted on December 19, 2023; while the most recently adopted territorial flag is that of the Northern Mariana Islands, adopted on July 1, 1985. The flag of the District of Columbia was adopted in 1938. Recent legislation in Massachusetts (2021) has started the process of redesigning their state flag. Illinois legislature will start the redesign process in September 2024. Maine and Michigan also have plans to redesign their flags in the future, but have not been confirmed.

Despite a variety of designs, the majority of the states' flags share the same design pattern consisting of the state seal superimposed on a monochrome background, commonly a shade of blue, which remains a source of criticism from vexillologists. According to a 2001 survey by the North American Vexillological Association, New Mexico has the best-designed flag of any U.S. state, U.S. territory, or Canadian province, while Georgia's state flag was rated the worst (the latter of which has been changed since the survey was conducted).