The Super Dual Auroral Radar Network (SuperDARN) of high frequency radars monitors ionospheric space weather at middle to high latitudes in both hemispheres. SuperDARN is an international collaboration involving scientists and engineers from over a dozen countries. The backscatter targets of interest are irregularities in the ionospheric plasma density that are aligned along the geomagnetic field. The Doppler motion of the irregularities can be used to infer the strength and direction of the ionospheric electric field. These measurements, obtained continuously, provide valuable information about the electrodynamics of the coupled magnetosphere-ionosphere system over extended spatial scales and with high time resolution. In this paper, the history of SuperDARN is briefly reviewed with a particular emphasis on the recent expansion of the network to middle and higher latitudes. A technique for assimilating multi-radar data to produce space weather maps of the hemispheric state of ionospheric plasma motion is also described.