The solar wind electric field near the earth has been computed for ~41/2 solar rotations, utilizing Heos 2 magnetometer and particle velocity data. A clear modulation is apparent as a function of the earth's position within interplanetary sectors. The electric field rises sharply at each sector boundary from a preboundary value of ~1 mV/m to peak values between ~3 mV/m and ~6 mV/m. A correlation is found with several phenomena in the polar cap ionosphere.