In the United States, a charter city is a city in which the governing system is defined by the city's own charter document rather than by state, provincial, regional or national laws. In locations where city charters are allowed by law, a city can adopt or modify its organizing charter by decision of its administration by the way established in the charter. These cities may be administered predominantly by residents or through a third-party management structure, because a charter gives a city the flexibility to choose novel types of government structure. Charter cities are similar in administrative structure to special administrative regions.