Sussex County is a county located in the southern part of the U.S. state of Delaware, on the Delmarva Peninsula. As of the 2010 census, the population was 197,145. The county seat is Georgetown. The first European settlement in the state of Delaware was founded by the Dutch in 1631 near the present-day town of Lewes on the Atlantic Coast. However, Sussex County was not organized until 1683 under English colonial rule. Sussex County is included in the Salisbury, MD-DE Metropolitan Statistical Area which encompasses much of central Delmarva.