This paper presents key signatures in the spatial distribution of ionospheric electron density attributed to solar wind particles injected following magnetopause reconnection. Using established criteria, optical auroral emissions have been used to identify the reconnection process. A simultaneous image of electron density shows an enhanced region with a northward gradient in F-layer peak height that may be linked to dispersion of precipitating soft ions. In addition, an E-region enhancement at lower latitude can be associated with precipitation of pitch-angle scattered ring current electrons on closed field lines. A narrow density enhancement extending into the high topside ionosphere may indicate the signature of a field-aligned current. Taken together, the features enable identification in the ionosphere of the open/closed field-line boundary. ¿ 1998 American Geophysical Union