In 1990, The U.S. Census Reported that 226,123 Iranian immigrants were living in the U.S., a growth of slightly under 100,000 in a tenyear period. These were individuals who either were born in Iran, or were of Iranian ancestry but born outside Iran in a country other than the U.S. The almost doubling of this population over a short period of time, combined with the group's variety of socioeconomic backgrounds, has created some of the most diverse ethnic geographies in the U.S.
Traditionally, academic theories have focused on issues regarding chain migration, port of entry, the assimilation process, ethnic economy, and labor market participation to explain the geographic distribution of various ethnic groups and their shifts over time.