Where Gig City Meets NASCAR: The 423 Area Code in Eastern Tennessee

The 423 area code covers the two eastern anchors of Tennessee — the Chattanooga metro in the southeast corner and the Tri-Cities region (Johnson City, Kingsport, and Bristol) in the northeast — in service since November 1995. Area code 423 is unusual in that it covers two geographically separate clusters: the 865 code for Knoxville sits between them, creating a territory that splits across eastern Tennessee like two islands in the same sea.

Chattanooga gained global recognition in 2010 as America's first Gig City — the first municipality in the United States to deploy city-wide 1 Gbps fiber internet. The Tri-Cities end of 423 hosts Bristol Motor Speedway, one of the most storied venues in NASCAR. No overlay has been added to 423; the single code has served both clusters since 1995. Time zone is Eastern (ET) throughout.

This guide covers what 423 serves, explains the split-territory geography, details Chattanooga's technology reinvention, and outlines the economy behind eastern Tennessee's two major metro areas.

What 423 covers — two clusters across eastern Tennessee

The 423 area code location is eastern Tennessee — but not as a single contiguous block. Area code 423 covers two distinct geographic clusters separated by the 865 Knoxville territory:

Southeastern cluster — Chattanooga metro:

Northeastern cluster — Tri-Cities:

What 423 does NOT cover:

• Knoxville and surrounding counties → 865
• Nashville and middle Tennessee → 615 and 629
• Memphis and western Tennessee → 901 and 731

Chattanooga: America's first Gig City

In 2010, the Electric Power Board of Chattanooga (EPB) switched on the United States' first city-wide gigabit fiber network — delivering 1 Gbps internet to every home and business in Chattanooga simultaneously. No other American city had accomplished this at municipal scale. The rollout cost approximately $330 million (partially funded by federal stimulus), covered all 600 square miles of EPB's service territory, and positioned Chattanooga as the most connected mid-size city in the country.

The practical outcomes of "Gig City" status transformed Chattanooga's economic identity:

Technology sector growth Within five years of the gigabit launch, Chattanooga attracted more than 400 technology startups and saw the establishment of the Chattanooga Technology Council, the Company Lab (Co.Lab) startup accelerator, and a string of venture investments targeting the city specifically because of its infrastructure advantage. Contact us to explore 423 numbers for your Chattanooga-area business presence.

Amazon fulfillment and logistics Amazon's decision to build a major fulfillment center in Chattanooga was directly influenced by the gigabit network's logistics and inventory management capabilities. The facility, combined with Chattanooga's position at the intersection of three major interstate highways (I-24, I-59, I-75), made it one of the most connected distribution hubs in the southeastern United States.

EPB Smart Grid EPB's fiber network does double duty — it powers not just consumer internet but the city's smart electrical grid, which uses sensors and automation to restore power outages in an average of 1.4 seconds compared to the national average of 90 minutes. The smart grid has saved Chattanooga businesses an estimated $100 million annually in avoided outage costs, making it one of the most quantifiable examples of broadband infrastructure driving economic value.

How area code 423 was created

January 1, 1947 — Tennessee launched with two original NANP codes: 615 for most of the state and 901 carved out for the Memphis area. For nearly four decades, 615 covered everything from Nashville east to the Appalachians, including the entire future 423 footprint.

1984 — 901 splits for Memphis As Memphis grew into a major logistics and commercial hub — anchored by FedEx's founding there in 1971 — western Tennessee's number demand separated from the Nashville-anchored 615. Area code 901 was created for Memphis and the western third of the state.

November 1995 — 423 created for eastern Tennessee Tennessee's remaining 615 pool faced exhaustion through the mobile phone surge of the early 1990s. Regulators split eastern Tennessee from Nashville as new code 423, covering the entire eastern third of the state — from Chattanooga in the south through Knoxville to the Tri-Cities in the north. It was a large, mountainous, economically diverse territory.

1999 — 865 splits for Knoxville Four years after its creation, the Knoxville metro corridor had grown enough to justify its own code. 865 was carved out to serve Knox County and the Knoxville region, leaving 423 with its current split-cluster geography: the Chattanooga metro in the southeast and the Tri-Cities in the northeast, with Knoxville's 865 occupying the middle.

Just as 415 shrank over decades from all of Northern California to just San Francisco and Marin, 423 contracted from all of eastern Tennessee to its two remaining anchor clusters.

What the 423 economy runs on

Eastern Tennessee's economy spans advanced manufacturing, specialty chemicals, motorsports tourism, and healthcare — bridging two distinct metro clusters:

Volkswagen Assembly Plant (Chattanooga) Volkswagen's Chattanooga assembly facility, which opened in 2011, is the German automaker's only US manufacturing plant producing vehicles for the North American market. The plant employs more than 3,500 direct workers and produces the VW Atlas and Atlas Cross Sport SUVs. Its 2023 announcement of a major expansion for EV battery production made Chattanooga one of the most significant electric vehicle manufacturing sites in the southeastern United States — a direct continuation of the Gig City economic transformation story.

Eastman Chemical Company (Kingsport) Eastman Chemical is the Tri-Cities' anchor Fortune 500 institution. Founded in Kingsport in 1920 as a division of Eastman Kodak, it became an independent company in 1994 and today generates more than $9 billion in annual revenue from specialty chemicals, advanced materials, and performance films used in industries from automotive to consumer goods. With more than 14,000 global employees and deep roots in Kingsport, Eastman is the single most consequential employer in northeastern Tennessee's 423 footprint.

Bristol Motor Speedway Bristol Motor Speedway — nicknamed "The Last Great Colosseum" — is one of the most celebrated venues in NASCAR racing. Its 0.533-mile concrete oval with steep 30-degree banking and a capacity exceeding 150,000 spectators makes it one of the largest sports venues in the United States by attendance. Twice-yearly NASCAR Cup Series races at Bristol generate more than $200 million in regional economic impact per event weekend. Bristol sits directly on the Tennessee-Virginia state line, with the start-finish line crossing the border.

ETSU, Ballad Health, and the Johnson City anchor East Tennessee State University (ETSU) in Johnson City enrolls more than 15,000 students and drives the knowledge economy of the northeastern 423 cluster. Its Quillen College of Medicine and the associated Ballad Health hospital system — one of the largest employers in the Tri-Cities — anchor the region's healthcare economy and provide the primary medical services across northeastern Tennessee and southwestern Virginia.

Is 423 in Tennessee? What state is it?

Yes — 423 is exclusively a Tennessee area code, covering the two eastern clusters of the state: Chattanooga in the southeast and the Tri-Cities in the northeast.

"423 area code state" is one of the most common 423 searches, reflecting the code's limited national recognition outside Tennessee and the Southeast. Unlike codes tied to globally known cities — 212 for New York, 415 for San Francisco — 423 serves mid-size metros without a single internationally dominant landmark. The code is well known throughout Tennessee and neighboring Georgia, Virginia, and North Carolina, but less familiar to callers receiving 423 contacts from outside the region.

"Calls from 423 area code" is particularly high-volume because Kingsport's Eastman Chemical and Chattanooga's growing business services sector generate significant outbound call volume to national accounts. A recipient in another state receiving a 423 call from a corporate number may search the code without recognizing the Tennessee origin.

"1 423 area code" is the international dialing format: the United States country code is +1, making a full Chattanooga number dial as +1 423 followed by seven digits.

423 area code ZIP codes

Common ZIP codes within the 423 coverage area:

Chattanooga 37401 · 37402 · 37403 · 37404 · 37405 · 37406 · 37407 · 37408 · 37409 · 37410 · 37411 · 37412 · 37415 · 37416 · 37419 · 37421

Cleveland 37311 · 37312 · 37320 · 37323

Athens 37303 · 37371

Johnson City 37601 · 37604 · 37614 · 37615

Kingsport 37660 · 37663 · 37664 · 37665 · 37669

Bristol, TN 37620 · 37621

Elizabethton 37643 · 37644

Greeneville 37743 · 37744 · 37745

Morristown 37813 · 37814 · 37816

Note: Knoxville ZIP codes (37901–37938) use area code 865, not 423 — the 865 Knoxville cluster sits between the two 423 regions.

Scam calls from 423 numbers

Robocallers spoof 423 numbers to reach targets in Tennessee, Georgia, Virginia, and North Carolina — the natural call footprint of eastern Tennessee businesses. Common spoofed 423 schemes include:

• Extended warranty and insurance calls — High-volume robocall campaigns using 423 numbers to appear local to Chattanooga or Tri-Cities recipients.
• Utility impersonation — Callers posing as EPB (Chattanooga's utility), Tennessee American Water, or TVA representatives threatening service disconnection.
• Automotive scams — Given Chattanooga's Volkswagen plant association, fraudulent callers claiming VW financing, recall notices, or extended service plans.
• Healthcare and Medicare scams — Targeting the large retiree population across Hamilton County and the Tri-Cities, using spoofed 423 numbers as a local credibility signal.
• Text scams (smishing) — Fraudulent 423 texts about package deliveries, prize notifications, or banking alerts with malicious links.

The FCC's STIR/SHAKEN call authentication framework requires carriers to verify caller ID before connecting calls. Any unsolicited 423 call that leaves no voicemail is almost certainly a spoof — legitimate eastern Tennessee businesses, utilities, and healthcare systems always leave a callback number.

Key takeaways

• 423 covers two separate clusters of eastern Tennessee: the Chattanooga metro (Hamilton, Bradley, McMinn counties) and the Tri-Cities (Washington, Sullivan, Carter, Hamblen counties) — in service since November 1995.
• Area code 865 (Knoxville) sits between the two 423 clusters; 423 was created when 615 split eastern Tennessee, and 865 was later carved out in 1999 for Knoxville.
• 423 has no overlay. A single code has served the entire eastern Tennessee footprint since 1995 without exhaustion.
• Chattanooga became the United States' first Gig City in 2010 when EPB deployed city-wide 1 Gbps fiber internet, triggering a technology and manufacturing renaissance that attracted Volkswagen, Amazon, and hundreds of startups.
• 423 is not in Georgia, Virginia, or North Carolina — it is exclusively Tennessee, despite the Tri-Cities' proximity to Virginia.
• Time zone: Eastern (ET) — EST (UTC −5) in winter, EDT (UTC −4) during Daylight Saving Time.
• The 423 economy spans Volkswagen Chattanooga (3,500+ jobs, EV expansion), Eastman Chemical (Kingsport Fortune 500, $9B+ revenue), Bristol Motor Speedway (NASCAR's colosseum, 150,000 seats), and ETSU / Ballad Health (Johnson City anchor institutions).

Frequently asked questions