If a flag touches the ground, the condition should be remedied as quickly as possible. If the flag has become dirty, it should be cleaned with a mild soap before being re-flown.The United States Flag Code says the flag must be kept from touching the ground, but contrary to popular belief, it does not require the flag to be burned if this happens.
Destroying a flag is only prescribed if a flag has become too dirty, tattered or otherwise damaged to be displayed properly. Flags that have reached the end of their lifespan are to be disposed of in a dignified manner, preferably by fire; however, many flags are made from nylon or other materials that produce toxic fumes when burned, and it may be illegal to burn a flag due to the potential for the release of dangerous pollutants. In this case, the flag can be turned over to the local Veterans of Foreign Wars chapter for proper disposal. In many cases, these chapters hold ceremonies on Flag Day where cotton or wool flags are burned and synthetic flags are buried with appropriate ceremony.
The Flag Code was established in 1942 by Franklin Delano Roosevelt. It came about in part due to the misuse of the flag on commercial packaging and advertising materials in the 19th century.