Complex sentence: Coolidge's family had deep roots in New England; his earliest American ancestor, John Coolidge, emigrated from Cottenham, Cambridgeshire, England, around 1630 and settled in Watertown, Massachusetts.
Split into simpler sentences: Coolidge's family had deep roots in New England. His earliest American ancestor, John Coolidge, emigrated from Cottenham, Cambridgeshire, England, around 1630 and settled in Watertown, Massachusetts.