The inferred polarity (toward or away from the sun) of the interplanetary magnetic field at earth using polar observations of the geomagnetic field has been compared with spacecraft observations. A list published by Svalgaard (1974) of the inferred field polarities during 1970--1972 is found to be correct on 82% of the days. A near real time (same day) method of inferring the polarity of the interplanetary magnetic field using geomagnetic observations at Vostok and Thule is in use at the NOAA Space Environment Laboratory, Boulder, Colorado. During 1972 this method is found to be correct on 87% of the days. A list of 'well-defined' sector boundaries at earth during 1970--1972 is given.