Complex sentence: Dorchester as a separate municipality would rank among the top five Massachusetts cities, a very diverse mix of Eastern Europeans, African Americans, European Americans, Irish American immigration, Caribbean Americans, Latinos, and East and Southeast Asian Americans.
Split into simpler sentences: Dorchester as a separate municipality would rank among the top five Massachusetts cities. It has a very diverse mix of Eastern Europeans, African Americans, European Americans, Irish American immigration, Caribbean Americans, Latinos, and East and Southeast Asian Americans.