A number of simulations have predicted a closed magnetosphere after several hours of northward interplanetary magnetic field (IMF). During January 7--8, 1998, the IMF was strongly northward for ~21 hours without any southward excursion. The Geotail spacecraft was located at -21 > Xgsm > -28 RE and very close to the magnetospheric equatorial plane and midnight, and detected two distinct regions. In the inner region close to the equatorial plane, the geomagnetic field is weak, the plasma pressure and plasma beta are high, and plasma flow is sunward. The outer region is characterized by lower plasma pressure and antisunward plasma flow. The observations are consistent with a closed magnetosphere and may represent the ground state of the magnetosphere.