In this paper we examine the relationship between geosynchronous magnetic field variations during substorms measured by GOES 5 and the auroral electrojet as measured by AE and Poste de la Baleine. As in previous studies, we find that the more taillike the field prior to the local onset, the greater the dipolarization of the field during the substorm. We also find that the greater the deviation of the field from a dipolar configuration, the larger the change in AE during the event. This implies that stronger cross-tail currents prior to the substorm are associated with larger substorm-associated westward electrojets and thus more intense substorms. Previous work has shown that in order to produce the observed taillike fields at geosynchronous altitude, the intense cross-tail current that builds up during the growth phase must be localized in the near-Earth (≤10 RE) region. Since the westward electrojet is the ionospheric leg of the substorm current wedge, our result implies that the substorm-associated westward electrojet is drawn from the near-Earth region. In fact, we find that most of the current diversion occurs in the near-Earth magnetotail. Furthermore, we estimate that a diversion about half of the near-Earth cross-tail current can account for the current in the northern and southern westward electrojets associated with the substorm current wedge. ¿ American Geophysical Union 1993