The addition of magnetic field measurements to the Atmosphere Explorer C data base enabled us to examine the relations between field-aligned currents (FAC), energetic particles, and plasma convection in the high-latitude ionosphere. We observe that in general, magnetic field perturbations extend throughout the regions of gradients in the plasma convection, particularly equatorward of the plasma convection reversal. A study of 13 dayside polar passes shows that the region 1 FAC's (Iijima and Potemra, 1976a) are observed to span the convection reversal and extend an average of 0.5¿ invariant latitude poleward of the reversal. Region 2 currents are observed entirely on sunward convecting plasma. Simultaneous observations of low-energy electron data (200 ev→25 keV) indicate that the poleward limit of the region 1 FAC's is nearly coincident with the high-latitude limit of 1-keV plasma sheet electrons. These observations are consistent with a model in which the dayside region 1 FAC's have a source that is at least partially due to a 'viscouslike'' interaction on closed field lines in the low-latitude magnetospheric boundary layer.