Area code 609 serves southern and central New Jersey, including cities such as Trenton, Princeton, Atlantic City, and parts of the Jersey Shore. It was one of the original area codes established in 1958 after splitting from 201. In 2018, area code 640 was introduced as an overlay to provide additional numbering capacity, requiring ten-digit dialing across the region. The 609 area is diverse, encompassing government centers, Ivy League universities, and coastal resort towns. It plays a critical role in state governance and tourism. While 640 now shares the region, 609 retains its status as the historic and cultural identifier of this key region in New Jersey.