This paper examines the relation between known crossings of the equatorward edge of the Earth's northern magnetic cusp during steady southward interplanetary magnetic field conditions, as recorded by the Magnetic Field Experiment onboard the Polar spacecraft, and the predicted location of the equatorwardmost open field line as given by two differing magnetic field models. These are the Rice Field Model, an analytic open magnetosphere field model; and the Tsyganenko 1996 data-based model. The two models that were considered display remarkably similar performance in how often they can locate the dayside equatorward edge of the cusp in three dimensions. However, the Rice Field Model is superior for ZGSM>5 RE, whereas the Tsyganenko 1996 model more accurately duplicates the observed range of cusp positions in the YGSM direction. The Rice Field Model and the Tsyganenko 1996 models also differ in predicting the magnetic field vectors in and around the cusp region. The former is more accurate at high latitudes on closed dayside field lines equatorward of the cusp; the latter is better at predicting the field direction on interconnected field lines. ¿ 2001 American Geophysical Union