Poplar Branch is a long 1st order tributary to Mill Creek in Pittsylvania County, Virginia.
Poplar Branch rises about 1.5 miles south-southwest of Gretna Rolling Mill, Virginia and then flows generally east to join Mill Creek about 1.5 miles southeast of Gretna Rolling Mill.
Poplar Branch drains of area, receives about 45.6 in/year of precipitation, has a wetness index of 410.64, and is about 49% forested.