How did Essex County get its name?

Answer 1

It's derived from East Saxon; there's also Sussex (from South Saxon) and Thomas Hardy's name for Dorset was Wessex (West Saxon).

Answer 2

Essex County in New Jersey is named after the English county of Essex. The city of Newark, one of the major cities in the county, was established by Puritans from Connecticut in 1666 and named after Newark-on-Trent in England, which is located in Nottinghamshire, neighboring the county of Essex.