Complex sentence: In addition, nearby Philadelphia, Pennsylvania had the largest population of free blacks in the North and no professional police force in the antebellum years, so residents, especially children because they were more easily controlled, were at risk from kidnappers.
Split into simpler sentences: In addition, nearby Philadelphia, Pennsylvania had the largest population of free blacks in the North and no professional police force in the antebellum years. Residents, especially children because they were more easily controlled, were at risk from kidnappers.