For the first time the full ionospheric signature of the lightning electromagnetic pulse (EMP) was measured up to a frequency of 2 MHz. At altitudes below 225 km, the upward-going whistler wave is found to have a nose-whistler wave shape with the fastest propagating frequency (nose frequency) near 80 kHz. The bulk of the EMP energy is at the nose frequency, and there is a sharp upper limit near 175 kHz where the group delay is very long. We believe the group delay is due to a propagation resonance for the whistler mode (slightly non-longitudinal propagation) associated with the low plasma frequencies in the F-layer valley. MF emissions were seen below the F peak, but not above. These results verify earlier speculation that the leading intense edge of the lightning EMP was carried by 50--125 kHz waves. In addition, we present tantalizing evidence for detection of a pulse pair prior to the stroke that is similar to transionospheric pulse pairs (TIPPs) detected in satellite data.¿ 1997 American Geophysical Union