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Project Map
US 421 Vicinity Map
Project Fast Facts
  • Status: Archive
  • County: Watauga
  • Type of Project: Widening
  • STIP Number: U-4020
  • Completion Date: 2011
  • Estimated Cost: Construction $16.2 million
  • Project Team: Blythe Development, Inc.
  • Incident(s): More Traffic Info...
    • Currently None
US421 Widening Logo


Widen 1.1 miles of U.S. 421 (King Street) to a four- to six-lane divided highway with a raised concrete median from U.S. 321 (Hardin Street) to east of N.C. 194 (Jefferson Road).

News and Updates

Current Construction Activities
Upcoming Construction Activities
  • Grading and prep work for retaining walls across from New Market Center
  • Temporary signal installation

Project Overview and Purpose

The purpose of this project is to help motorists get where they need to go more efficiently in Boone and along the project study corridor.

U.S. 421 is the primary east-west route in northwestern North Carolina. The U.S. 421 (King Street) corridor through Boone intersects U.S. 321, U.S. 221, N.C. 194 and N.C. 105.

Because there are so many routes that intersect U.S. 421, the project corridor acts as a funnel for traffic through Boone and between the Triad, Hickory, Asheville, the Charlotte area and the Tri-Cities in Tennessee. Both U.S. 321 and U.S. 221 intersect U.S. 421 as five-lane highways. U.S. 421 east of the project corridor is also a five-lane road. Within the project corridor, U.S. 421 (King Street) is a four-lane highway from N.C. 194 to U.S. 221/N.C. 105. Between U.S. 221/N.C. 105 and U.S. 321 (Hardin Street), U.S. 421 is a narrow two-lane road.

NCDOT proposes to widen U.S. 421 (King Street) to a six-lane divided highway from Grove Street (east of N.C. 194) to U.S. 221/N.C. 105. From U.S. 221/N.C. 105 to U.S. 321 (Hardin Street), U.S. 421 will be a four-lane divided highway. Additional improvements include:

  • Constructing 12-foot wide inside travel lanes and 14-foot wide outside travel lanes to accommodate bicycles;
  • Building five-foot wide sidewalks along both sides of the highway;
  • Separating opposite direction travel lanes by a continuous four-foot wide concrete median. The median will be 17.5-foot wide between the double left-turn lanes at U.S. 321 and U.S. 221/N.C. 105, because there is not enough distance to reduce its width significantly; and
  • Realigning Daniel Boone Drive to tie into the existing U.S. 421-221/N.C. 194 intersection.

Project Visualizations


A video simulation of the proposed long-term improvements for the U.S. 421 widening project are shown here.

You need the Flash player and JavaScript enabled to view this video. You can also try viewing in our NCDOT Youtube channel.


The Department is proposing to construct tiered retaining wall adjacent to the Country Inn Suites. The widening of US 421 will require the removal of a substanial amount of earth and the construction of the retaining walls will limit encroachment on the property.

Tiered Wall Visualization Tiered Wall Visualization

Project Photos

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Contact Information

Frank Gioscio, P.E.
Division 11 Engineer

Trent Beaver, P.E.
Division 11 Construction Engineer

Resources for Local Property Owners

In many cases, it is inevitable that a certain amount of private property must be acquired. The displacement of homes and businesses is minimized to the extent practicable. The following brochures will answer questions about this process.