Jin Sook Chang, who immigrated from Korea and with her husband Do Won launched clothing retailer Forever 21, now with nearly 500 stores.

FORBES: How The Self Made Women On The Forbes 400 Earned Their Fortunes

Other notable American newcomers include Do Won and Jin Sook Chang, the cofounders of Forever21, and Chris Cline, who owns 3 billion tons of coal reserves, mostly in Illinois.

FORBES: The World's Billionaires 2011: Inside The List

The privately held retailer is owned by husband and wife, Do Won (Don) Chang and his wife Jin Sook Chang, who moved to the U.S. from South Korea in 1981 and eventually became U.S. citizens.

FORBES: Forever 21 Is Donating $2 Million To Japan