640 Area Code: A Complete Guide to Central and Southern New Jersey

Quick answer: Area code 640 is the all-services overlay for area code 609, covering central and southern New Jersey including Mercer, Burlington, Ocean, Atlantic, and Cape May counties. Its major cities include Trenton, Princeton, Hamilton, Atlantic City, Toms River, and Cape May. Activated on September 17, 2018, it shares identical territory with 609, requires ten-digit dialing for all local calls, and operates in the Eastern Time Zone.

Which part of New Jersey does the 640 area code cover?

Area code 640 covers the central and southern half of New Jersey — a territory that spans from the Delaware River corridor and the state capital in Trenton, across the Pinelands and coastal plain, to the Atlantic Ocean shoreline and the barrier-island resort communities of the Jersey Shore. The 640 overlay mirrors area code 609 precisely: every city, township, and borough served by 609 is also served by 640.

The northern boundary of the 640 territory follows the division that separated central NJ from the northern counties served by 201 and its successors. The western and southwestern boundary is defined by the split that created area code 856 in 2001, which carved off Camden, Gloucester, Salem, and Cumberland counties from the 609 territory.

What remained — and what 640 now overlays — is the arc of counties running from Mercer at the center through Burlington's vast inland expanse, south to Atlantic, Cape May, and east to Ocean County's coastal communities.

This geography puts the 640 area code in immediate proximity to major northeastern economic hubs. Like the 636 area code — which similarly serves a large suburban and exurban ring around a major city — 640 covers a territory that blends dense state-government and university corridors with coastal resort economies, military installations, and rapidly growing suburban communities.

Cities and counties in the 640 and 609 service area

The 640 and 609 service area covers five full counties and portions of others across the central and southern New Jersey coastal plain and Delaware River valley, reaching from the state capital to the Atlantic Ocean.

Counties and key communities in the 640 area code:

• Mercer County — The governmental and academic heart of the 640 territory. Home to Trenton (the New Jersey state capital), Princeton (one of the world's foremost research universities), Hamilton Township, Ewing Township, and Lawrence Township. The US Route 1 corridor through Mercer County hosts one of the most productive pharmaceutical and life-sciences research clusters in the northeastern United States, with numerous biotech firms, clinical research organizations, and technology companies positioned between Princeton and Trenton
• Burlington County — The largest county by area in New Jersey, stretching from the Delaware River east to the Pinelands. Anchored by Mount Holly (the county seat), Medford, Moorestown, Evesham, and Mount Laurel — major suburban communities with strong retail, healthcare, and professional services bases. Burlington County is also home to Joint Base McGuire-Dix-Lakehurst, the combined military installation formed from three former separate bases and now one of the most strategically significant military installations on the East Coast
• Ocean County — New Jersey's fastest-growing county, anchored by Toms River (the county seat), Lakewood, Brick Township, Jackson, and Barnegat. Ocean County drives a large service, retail, and healthcare economy; Barnabas Health's Community Medical Center is a major regional employer. The county's barrier islands — including Seaside Heights, Island Beach State Park, Long Beach Island, and the surrounding barrier beach communities — form one of the most visited Jersey Shore resort corridors
• Atlantic County — The gaming and convention hub of the 640 territory, anchored by Atlantic City, which hosts nine operating casinos along the Boardwalk including major resort properties, the Atlantic City Convention Center, and Atlantic City International Airport. The county also includes Hammonton, Mays Landing, Pleasantville, and Absecon
• Cape May County — The southernmost county in the 640 territory and one of New Jersey's most celebrated tourist destinations. Home to Cape May city (America's oldest seaside resort and a National Historic Landmark), Ocean City, Wildwood, Avalon, Stone Harbor, and Cape May Point — a Victorian architecture showcase, whale-watching destination, and birding hotspot at the tip of the New Jersey peninsula

Key cities by county:

How New Jersey's 640 overlay came to be

The 640 area code's origins trace back more than 70 years to the earliest days of the North American Numbering Plan. When NANPA launched in 1947, the entire state of New Jersey was assigned a single area code: 201. As New Jersey's population and telecommunications infrastructure expanded through the postwar decades, that single code became increasingly strained.

The first major relief came in 1956, when area code 609 was split from 201 to serve the central and southern portions of the state — roughly everything south of the Raritan River corridor. Area code 201 retained the northern half of New Jersey. For the following decades, 609 served as the sole prefix for a sprawling territory that included the state capital, major resort cities, an Ivy League university, and the entire southern coastal plain.

By 2001, 609's territory had grown dense enough to justify a further geographic split: area code 856 was carved from 609 to serve southwestern New Jersey — the Camden, Gloucester, Salem, and Cumberland county cluster. This reduced 609's footprint to the five-county zone it covers today. The New Jersey Board of Public Utilities, which oversees telecommunications policy for the state in coordination with NANPA, monitored remaining capacity in the streamlined 609 territory as mobile and VoIP subscriber growth through the 2010s again pushed available prefixes toward exhaustion.

The solution approved was an all-services overlay: area code 640, activated on September 17, 2018. No existing 609 numbers changed. Ten-digit dialing became mandatory across the entire territory — all local calls require the full ten digits regardless of whether the destination is a 609 or a 640 number.

Key milestones:

• 1947 — Area code 201 assigned to all of New Jersey
• 1956 — Area code 609 split from 201 for central and southern NJ
• 2001 — Area code 856 split from 609 for southwestern NJ (Camden, Gloucester, Salem, Cumberland counties)
• September 17, 2018 — Area code 640 activated as all-services overlay for 609
• Present — 609 and 640 share identical territory; all new lines may receive either prefix

How to place and receive 640 calls

Because 640 and 609 are overlays sharing the same geographic territory, ten-digit dialing is mandatory for every local call — even between two numbers that share the same exchange prefix within the same town.

Time zone note: The entire 640 territory observes Eastern Time — the same zone as New York City, Philadelphia, Boston, and Washington, D.C. Callers from the Central Time Zone are one hour behind; callers from the Pacific Coast are three hours behind. Given that much of the 640 footprint is deeply integrated with the Philadelphia and New York metropolitan economies, most business contacts will already be operating in Eastern Time.

Why a 640 number strengthens your New Jersey presence

The 640 area code reaches one of the most economically diverse and densely networked territories in the northeastern United States — combining Ivy League research infrastructure, major pharmaceutical and biotechnology activity, a large military and defense contracting base, one of the nation's best-known resort and gaming economies, and a rapidly growing suburban professional population.

Key reasons to establish a 640 area code number:

• Princeton University and the Route 1 pharma corridor — Princeton University's research enterprise and its affiliated technology transfer ecosystem anchor a dense cluster of pharmaceutical, biotechnology, and clinical research firms along the US Route 1 corridor through Mercer County; major employers in or adjacent to the 640 footprint have long included Bristol-Myers Squibb, Novo Nordisk, and dozens of biotech and contract research organizations — making the 640 prefix highly credible with life-sciences and professional services buyers in the Princeton and Trenton markets
• Joint Base McGuire-Dix-Lakehurst — The combined Burlington County military installation, formed from three formerly separate Air Force, Army, and Navy bases, is one of the most strategically significant military and defense employment centers on the East Coast; its presence anchors a substantial defense contracting, logistics, and government services economy across Burlington County and the broader 640 territory
• Atlantic City gaming and convention economy — The nine operating casinos along the Atlantic City Boardwalk, the Atlantic City Convention Center, and the city's international airport collectively generate billions in annual economic activity; hospitality, event services, food and beverage, and related professional services businesses serving this market benefit directly from the local caller-ID credibility that a 640 number provides
• Jersey Shore and Cape May tourism — Ocean County's barrier island communities and Cape May's Victorian resort city represent one of the most heavily visited tourism corridors in the northeastern United States, driving year-round hospitality, real estate, retail, and seasonal staffing markets across the southernmost 640 counties
• UCaaS virtual NJ expansion — Businesses targeting the 640 territory's pharmaceutical, defense, gaming, or professional services markets can establish immediate Trenton, Princeton, or Atlantic City credibility through a Unified Communications as a Service (UCaaS) platform, which provisions a 640 number with cloud-hosted voice, video, messaging, and analytics — routing every inbound call to any device anywhere in the world with no physical New Jersey office required; UCaaS also pairs the 640 presence naturally with a 475 area code number for companies building simultaneous reach across the broader Northeast corridor into Connecticut's Fairfield and New Haven county markets

Recognizing fraudulent calls from 640 numbers

Area code 640 is actively spoofed by scammers using neighbor spoofing — a technique that matches the displayed caller ID to the target's local area code and prefix to increase the likelihood of the call being answered. Several fraud categories are disproportionately associated with 640 numbers.

Most frequently reported 640 scam types:

• Medicare and Medicaid fraud — The single most reported scam category in the 640 area code, with callers posing as Medicare representatives, Medicaid case workers, or healthcare billing departments to extract insurance card numbers, Social Security digits, or personal financial information; particularly prevalent across Ocean County and Atlantic County communities with large retired and fixed-income populations
• Solar panel and energy upgrade scams — Callers claiming to represent utility providers, state energy programs, or government solar initiatives pressure targets into scheduling home visits or providing financial details in exchange for fabricated federal incentives or discounts on solar installations; New Jersey's active residential solar market makes the pitch credible enough to deceive many residents
• Auto warranty extension calls — Prerecorded calls claiming a vehicle warranty has expired or is expiring imminently and demanding immediate credit card payment to extend coverage; these calls are heavily reported across Burlington and Ocean county suburban communities, targeting the large commuter vehicle population in the corridor
• Health insurance marketplace fraud — Callers posing as ACA marketplace navigators, insurance brokers, or government healthcare enrollment specialists collect plan selection details, Social Security numbers, and payment credentials under the pretense of enrolling targets in subsidized coverage — a category that spikes annually around open enrollment periods
• Amazon, Reader's Digest, and sweepstakes fraud — Callers or text messages inform targets that they have won a prize, loyalty reward, or contest payout, then demand an advance payment via gift card or wire transfer to release the award; no legitimate retailer or sweepstakes organization collects money from winners before delivering a prize

How to stay protected:

• Medicare, Medicaid, and Social Security never request sensitive information by phone — hang up and call the official number listed on your insurance card or at medicare.gov
• No legitimate government energy or solar program demands same-day financial commitments over the phone
• Report suspected 640 scam calls to the FTC at reportfraud.ftc.gov and to the New Jersey Division of Consumer Affairs at njconsumeraffairs.gov

640 area code snapshot: essential facts

• Area code 640 is the all-services overlay for area code 609, covering central and southern New Jersey including Mercer, Burlington, Ocean, Atlantic, and Cape May counties
• It was activated on September 17, 2018 — no existing 609 numbers changed when 640 launched
• Ten-digit dialing is mandatory for all local calls in the 640/609 territory; callers must dial all ten digits even between neighbors sharing the same exchange
• The entire 640 territory observes Eastern Time — the same zone as New York City, Philadelphia, and Washington, D.C.
• Major economic anchors include Princeton University, the Route 1 pharma corridor, Joint Base McGuire-Dix-Lakehurst, the Atlantic City casino and convention economy, and the Jersey Shore tourism corridor
• The most reported scam types in 640 are Medicare/Medicaid fraud, solar panel scams, auto warranty calls, and health insurance marketplace fraud
• 640 shares its territory with 609, and both prefixes are equally valid for lines, mobile numbers, and VoIP services in the service area

Frequently asked questions