U.S. Route 23 (US 23) is a part of the United States Numbered Highway System that travels from Jacksonville, Florida, to Mackinaw City, Michigan. In the U.S. state of Tennessee, the highway travels 57.48 miles (92.51 km) in the northeastern part of the state from the North Carolina state line at Sam's Gap in the Bald Mountains to the Virginia state line in Kingsport. The entire route in Tennessee is a four-lane controlled-access highway and is concurrent with Interstate 26 (I-26) for most of its length. The freeway is also designated the James H. Quillen Parkway for its entire length in Tennessee. US 23 in Tennessee is part of Corridor B of the Appalachian Development Highway System (ADHS) and serves as a major thoroughfare in the Tri-Cities region of the state. Although I-26 is technically an east–west route, the highway predominantly travels in a north–south alignment in the state. The highway reaches a maximum elevation of 3,760 feet (1,150 m) at the North Carolina state line, which is the highest elevation on the Interstate Highway System east of the Mississippi River.