The spatial relation between an open polar cap and the footprints of open magnetopause patches is calculated for a variety of IMF orientations. Patches mapped from an otherwise closed magnetopause elongate and fan out fromthe cusp point located at noon on the polar cap boundary. The fan extends into the closed field region equatorward of the polar cap. The footprints of patches well down the flanks elongate the most and align with the polar cap boundary. As the patches convect with the magnetosheath flow, their footprints pivot antisunward about the cusp until they coalesce with the polar cap. In the course of pivoting, the footprints act like paddles and push adjacent closed flux antisunward, forming a low latitude boundary layer on open and closed field lines. If the patches are regions of enhanced flux imbedded in an open magnetopause, the footprints shorten, detach fromthe cusp, and extrude from positions increasingly displaced from noon as the field component normal to the magnetopause strengthens. Only if the normal component is large will the footprints degenerate to bulges on the polar cap boundary and move directly poleward, as previously supposed. ¿American Geophysical Union 1990