States flags were designed independently by the governments of each state to serve as recognizable symbols of their states' unique qualities. The design of each flag is meant to represent some aspects of the identity of the state.
While some states have used a unique state flag since the 1700s, most U.S. states were motivated to design a state flag because of the 1893 World Exposition in Chicago. Faced with an opportunity for exposure to visitors from all over the world, many states wanted to have a flag that made them instantly identifiable. Between this time and the first world war, most of the modern state flags were created, though many have been changed over time since then.
The methodology of designing a state flag varies based on individual design trend between states, but the basic strategy for state flag design has been the expression of one or more symbols that represents a major aspect of the state's identity.
New Mexico's flag, for example, is a stylized Native American symbol, representing the strong indigenous presence in the state. Many states, including Vermont, Montana and Kansas, have placed their state seals centrally on their flags, depicting aspects of life, major industries and recognizable landscapes of the state, in order to express a unique state identity.