Data from four auroral sounding rockets, which directly measured field-aligned currents with particle detectors, are presented. The largest fraction of the field-aligned current carried by electrons was 1) due to precipitating electrons of energy <1 keV; 2) located spatially at the edges of the auroral luminosity. A model is suggested in which these currents couple the ionosphere to the magnetosphere and produce the pre-breakup auroral arc.