Electric field spectrum measurements from the plasma wave instrument on the Dynamics Explorer 1 spacecraft are used to study the local electron density at high altitudes in the northern polar cap region. The electron density is determined from the upper cutoff of whistler mode radiation at the electron plasma frequency. Median density values over the polar cap at L greater than 10 are found to vary from 35.2¿8.5 cm-3 at 2.1 RE to 0.99¿0.51 cm-3 at 4.66 RE. The steady state radial outflow model is examined for consistency with the observed density profile. A power law fit to the radial variation of the electron density yields an exponent of -3.85¿0.32, which for the radial outflow model implies a flow velocity increasing nearly linearly with increasing radial distance. Comparison of the observed electron densities with theoretical polar wind densities yield consistent results up to 2.8 RE. A comparison of the observed electron densities with low-altitude density profiles from the Alouette II and ISIS I spacecraft illustrate transitions in the slope of the profile at 1.16 RE and between 1.55 and 2.0 RE. The changes in the density profile suggest that changes occur in the basic radial transport processes at these altitudes.