Internal migration describes moves within a country. In the United States, people must move across a county line to be an official migrant. Net migration, the difference between the number of people moving in and out, may be positive or negative. Between 1990 and 1997, Florida had a net gain of 1.3 million people through migration, while New York state suffered a net loss of 673,000 people. The United States as a whole experienced a net immigration of 5.6 million people from abroad between 1990 and 1996.
Most moves are local, short-distance moves.
International moves are the least common. The U.S. mobility rate, or percentage of the population who moved during the past year, has varied between 16 percent and 21 percent since 1947. Americans are more mobile than residents of most other countries. In Japan, for example, only 4 percent of the population over age 1 moved to a new residence in 1996. Longer distance moves are primarily for economic reasons such as seeking a new job or accepting a corporate transfer.