Clarkston is a city in DeKalb County, Georgia, United States. The population was 7,554 as of the 2010 census. The city is home to a campus of Georgia State Universities Perimeter College.The city is noted for its ethnic diversity, and is often referred to as "the most diverse square mile in America" and "the Ellis Island of the South." In the 1990s refugee resettlement programs identified Clarkston as a good fit for displaced persons of many backgrounds. The rental market was open, residents were moving farther out from the Atlanta urban core, and Clarkston was the last stop on a transit line into the city. By the 2000s the local high school had students from more than 50 countries; a local mosque had 800 worshipers; and by some estimates, half the population was from outside the U.S.