After passing through the Clarksville Historic District, US 15, US 58 Business, and SR 49 leave the town of Clarksville by crossing the John H. Kerr Reservoir, an impoundment of the Roanoke River that is also known as Buggs Island Lake, on the Phillip Saint Julian Wilson Bridge and a causeway. The bridge, which contains lights underneath used for nighttime fishing, includes a brief passage through Halifax County due to the thalwegs of the Roanoke and Dan Rivers, which were used to set the county boundaries, converging just south of Clarksville. At the east end of the causeway, access to US 58 is provided at a four-way intersection. Ramps to US 58 west and US 58 east form the southern and eastern legs of the intersection, which mainline US 58 avoids via a pair of flyover ramps just east of its bridge over the reservoir. US 15 and SR 49 turn north, cross over the Virginia Southern rail line, and parallel the eastern shore of the lake until the two highways split at the hamlet of Dortch Store.