Drill rods and systems for use in drilling processes, as well as methods for making and using such drill rods and systems. A drill rod configured for sonic drilling operations can include a cylindrical body having an interior surface and an exterior surface. A first connector may be located on a first end of the cylindrical body and a second connector may be located on a second end of the cylindrical body. The first connector and the second connector can be complementary. The drill rod can include a helical feature and a corresponding helical channel on the exterior surface of the cylindrical body. The helical feature and corresponding helical channel can be configured for moving material displaced during a drilling operation in an axial direction away from one end of the drill rod to the other.