Previous studies of magnetic field perturbations at very high latitude have indicated the presence of an equivalent current system which is strongly modulated by the azimuthal (By) component of the interplanetary magnetic field. This current system is now thought to flow in the portion of the ionosphere to which the polar cusp (or cleft) maps. In this paper we shall show that, while the By component of the interplanetary magnetic field does not significantly change the total current flowing in the magnetosphere, it does redistribute the ionospheric portion of the current flow. This redistribution results in eastward ionospheric current being observed in the prenoon quadrant on the poleward side of the normally present westward electrojet when By >0, whereas only westward current flows in the prenoon quadrant when By <0.