Rocket observations of the lower ionosphere in the winter 1971 at two locations show differences of electron density which are attributed to enhancements of nitric oxide and energetic electron fluxes precipitated into the mesosphere during the poststorm phase of a geomagnetic storm. Electron density distributions were observed above Wallops Island, Virginai, and Keweenaw, Michigan, larger values occurring at Keweenaw. Energetic electron fluxes were greater at Keweenaw (L=3.9) than at Wallops Island (L=2.5). While particle ionization was the dominant factor in establishing the electron density during one measurement at Keweenaw, particles were not present 2 day earlier, even though the electron density distribution was significantly larger than that observed at Wallops Island on both occasions. An accompanying ion composition profile measured at Keweenaw during the earlier flight showed NO1 to be the dominant ion to 76 km, where the concentration of hydrated ions, H3O1⋅ (H2O)n, exceeded that of NO. This lowering of the transition height from NO1 to hydrated species is in agreement with independent observations of D region ion composition during anomalous winter conditions.