The flags of the U.S. States exhibit a variety of regional influences and local histories, as well as different styles and design principles. Nonetheless, 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.

The most recently adopted state flag is that of Mississippi, adopted on January 11, 2021.

Modern U.S. state flags as contemporarily understood date from the turn of the 20th century, when states wanted to have distinctive symbols at the 1893 World’s Columbian Exposition in Chicago, Illinois. Most U.S. state flags were designed and adopted between 1893 and World War I.

According to a 2001 survey by the North American Vexillological Association, New Mexico has the best-designed flag of any U.S. state, while Georgia's state flag was rated the worst design (Georgia adopted a new flag in 2003; Nebraska's state flag, whose design was rated second worst, remains in use to date).