	Crab Run begins in Barry Township, not far from the census-designated place of Beurys Lake. It flows west-northwest for several tenths of a mile and passes through a pond or small lake before turning north-northeast. After several tenths of a mile, the stream receives an unnamed tributary from the left and turns northeast. Several tenths of a mile further downstream, it receives an unnamed tributary from the right and turns north-northwest for a few tenths of a mile, flowing alongside the base of a mountain. The stream then turns north-northeast for a short distance, passing through a pond or small lake before reaching its confluence with Mahanoy Creek.