High Quality Content by WIKIPEDIA articles! Suffolk County is a county of Massachusetts. As of 2008, the population was estimated by the US Census Bureau to be 732,684; an increase from its population in 2000 of 689,807. The county seat is Boston, the state capital and largest city.The county was created by the Massachusetts General Court on May 10, 1643, when it was ordered "that the whole plantation within this jurisdiction be divided into four shires". Suffolk initially contained Boston, Roxbury, Dorchester, Dedham, Braintree, Weymouth, and Hingham