We present a model of the three-dimensional current system in the nighttime sector during the expansion phase through early recovery phase for bulge-type aurora substorms. The height-integrated horizontal ionospheric currents are calculated from models of the height-integrated conductivity and convection electric field previously published <Gjerloev and Hoffman, 2000a, 2000b, 2001> that were based on a set of data from the Dynamics Explorer 2 satellite, while the field-aligned currents are deduced from the divergence of the horizontal currents. These model-derived field-aligned currents are then compared with the field-aligned currents determined from magnetometer data from the same data set used to develop the conductance and electric field models. The comparison shows good agreement, thereby serving as an independent verification of the entire self-consistent substorm model. We find that the feeding as well as the drainage of the substorm current wedge component of the westward electrojet is principally due to an imbalance of the downward region 0 and upward region 1 current sheets under which the electrojet is flowing. We do not find evidence of a simple downward current postmidnight and upward current premidnight. The eastward electrojet, which almost entirely originates on the dayside, is partly drained by a poleward current flowing across the Harang region into the westward electrojet at ~19--21 magnetic local time (MLT) and partly by net upward field-aligned currents located just prior to midnight.