Complex sentence: The organization has its roots in Brooklyn, New York, where Margaret Sanger opened the first birth-control clinic in the U.S., and founded the American Birth Control League in 1921, which in 1942 became part of the Planned Parenthood Federation of America.
Split into simpler sentences: The organization has its roots in Brooklyn, New York, where Margaret Sanger opened the country's first birth-control clinic. Sanger founded the American Birth Control League in 1921, which in 1942 became part of the Planned Parenthood Federation of America.