Simplify the following text for a Grade 11 native English-speaking person.
Original: Because of 20th century African American migration from the South , a large African-American urban population lives in most of the region 's major cities , although the concentration is not generally as large as that of the Southern United States .
Simplified: Because of 20th century African American migration from the South , many African Americans live in most of the area 's large cities .