City through a zone while bypassing the downtown area. After Mountain City, begins the two mountain ranges and in between them is the area of Shady Valley. The two ranges are a popular motorcycle route known as "The Snake". More than 400 curves over an approximately ride. After the second mountain range, it flattens out after the South Fork Holston River heading towards Bristol. US 421 enters Virginia on the Old Dominion side of Bristol. Major highway junctions between the NC and VA state lines are State Route 67 (SR 67) in Mountain City, SR 91 the new Mountain City bypass, SR-394, and US 11E. Virginia US 421 enters from Tennessee in Bristol and goes west to Weber City, Duffield, and Pennington Gap in Southwest Virginia. The route goes through the Cumberland and Powell Mountains, and goes by Natural Tunnel State Park near Duffield. Kentucky US 421 enters the Bluegrass State running from the Pennington Gap area in Virginia into Harlan County. For the distance between the Virginia state line and closer to Hal Rogers Parkway, it is a major north-south two-lane highway. However, its passing zones are largely limited to a stretch after the Virginia line, through Harlan and along US 119. US 421 then crosses Pine Mountain and enters Leslie County, turning west at Hyden and paralleling the Hal Rogers Parkway. Between Manchester and McKee, US 421 functions as more of a local road with many curves. The roadway improves as it descends from the Cumberland Plateau into the Bluegrass Region at Big Hill in Madison County near Berea. It joins US 25 at the Blue Grass Army Depot south of Richmond and roughly parallels I-75 towards Lexington. Through Lexington, it is Richmond Road, Main Street and Leestown Road. The segment between Lexington and Frankfort was once designated Kentucky Route 50 (KY 50). US 62 runs briefly with US 421 in this section. In Frankfort, US 421 runs with US 60 on the west side of town, then runs within the city's northern bypass, briefly joining US 127. US 421 then traverses the very hilly area northwest of Frankfort, then through Henry and Trimble counties, exiting the state at Milton, crossing the Ohio River into Madison, Indiana via the Milton–Madison Bridge. Indiana US 421 winds through the southern part of Indiana as it runs from Madison, in the southeastern part of the state, to Indianapolis. North of Greensburg,