This article describes the evolution of the flag of the United States, as well as other flags used within the country, such as the flags of governmental agencies. There are also separate flags for embassies and boats.
Since 1818, a star for each new state has been added to the flag on the Fourth of July immediately following each state's admission. In years which multiple states were admitted, the number of stars on the flag jumped correspondingly; the most pronounced example of this is 1890, when five states were admitted within the span of a single year (North Dakota, South Dakota, Montana, and Washington in November 1889 and Idaho on July 3, 1890). This change has typically been the only change made with each revision of the flag since 1777, with the exception of changes in 1795 and 1818, which increased the number of stripes to 15 and then returned it to 13, respectively.
As the exact pattern of stars was not specified prior to 1912, and the exact colors not specified prior to 1934, many of the historical U.S. national flags shown below are typical rather than official designs.
Many agencies, departments, and offices of the U.S. federal government have their own flags, guidons, or standards. Following traditional American vexillology, these usually consist of the agency's departmental seal on a blank opaque background, but not always.
Every U.S. state also have flags of their own. As examples, here are the six highest-rated U.S. state flags in terms of design quality, according to a 2001 survey by the North American Vexillological Association (NAVA).
The U.S. national flag is the official flag for all islands, atolls, and reefs comprising the United States Minor Outlying Islands. However, unofficial flags are in use on five of these eleven insular areas:
Since 1777, the national ensign of the United States has also simultaneously served as its national flag. The current version is shown below; for previous versions, please see the section Historical progression of designs above.