Intense Pedersen and Hall currents in the sunlit cleft and polar cap ionosphere are determined from rocket-borne plasma, electric field, and magnetic field magnitude measurements and from recordings at nearby magnetic observatiories. The ionospheric conductivities are calculated from a model atmosphere, the international geomagnetic reference field,and the E and F1 region electron density and temperature observations. Current densities are calculated from these conductivities and the observed dc electric fields by Ohm's law. The height profile of the polar cap current densities agree in peak magnitude and height, and they indicate a peak Hall current of 34&mgr;A/m2 at 107-km altitude. A significant Pedersen current flows above this Hall current. The magnetic field at the earth's surface of the height-integrated current system is calculated; only the Hall component compares favorably in magnitude and direction with that obtained from local magnetic observatories. Field-aligned currents are estimated, and they may be present at the polar edge of the cleft coincident with a discontinuity in the electric field and the influx of ?500-eV electrons. Joule heating of the sunlit polar cap upper atmosphere is determined and found to be very intense and comparable to that of a disturbed auroral zone.