Complex sentence: In northern Westchester, the Hendrick Hudson Council serving the Ossining area and the Fennimore Cooper Council serving the White Plains area merged to form the Washington Irving Council in the early-1950s.
Split into simpler sentences: In northern Westchester, there was the Hendrick Hudson Council serving the Ossining area and the Fennimore Cooper Council serving the White Plains area. These two later merged to form the Washington Irving Council in the early-1950s.