Continuing to the northeast, the highway enters Panola County, in which it has junctions with  FM 348,  FM 1971, and  FM 1970 in the community of Clayton. SH 315 then enters Carthage, where it intersects  SH 149.
As one travels northeast, the highway enters Panola County, intersecting with several roads, including FM 348, FM 1971, and FM 1970, in the town of Clayton. The highway then passes through Carthage, crossing over SH 149.