Thames County is located in the province of Ontario, Canada and is named after the River Thames. The county seat is Chatham-Kent and its largest city is London. The county is bordered by Elgin County to the west, Middlesex County to the north, Oxford County to the east, and Essex County to the south. Essex County is a county in Southwestern Ontario, Canada, with a population of over 400, 000 people. It is bordered by Kent County to the east, Lambton County to the west, and Chatham-Kent to the north. The county seat is the city of Windsor.