A missing person is a person who has disappeared for no known reason.
Missing persons' photographs may be posted on bulletin boards, postcards, and websites, along with a phone number to be contacted if a sighting has been made.
People disappear for many reasons. Some individuals choose to disappear alone; most of these soon return. About 10% of missing persons in the United States never return, however. Reasons for this include:
By the end of 2005, there were 109,531 active missing person records according to the US Department of Justice. Children under the age of 18 account for 58,081 (53.03%) of the records and 11,868 (10.84%) were for young adults between the ages of 18 and 20.
During 2005, 834,536 entries were made into the National Crime Information Center's missing person file, which was an increase of 0.51% from the 830,325 entered in 2004. Missing Person records that were cleared or canceled during the same period totaled 844,838. The reasons for these removals include: a law enforcement agency located the subject, the individual returned home, or the record had to be removed by the entering agency due to a determination that the record is invalid.
A common misconception is that a person must be absent for 72 hours before being legally classed as missing, but this is rarely the case; in instances where there is evidence of violence or of an unusual absence, law enforcement agencies often stress the importance of beginning an investigation promptly.
In most common law jurisdictions a missing person can be declared dead in absentia (or "legally dead") after seven years. This time frame may be reduced in certain cases, such as deaths in major battles or mass disasters such as the September 11, 2001 attacks.