During 1957, as part of the program of the International Geophysical Year, the University of Iowa conducted a survey of cosmic ray intensity with equipment on balloon-launched rockets (''rockoons'') over the range of geomagnetic latitude &lgr; from 86 ¿N to 73 ¿S. This paper reports the results obtained up to altitudes of about 25 km during the flights of 26 balloons. The epoch of the observations was near the time of maximum solar activity. A comparison is made with similar observations at &lgr;=52¿ in 1953 at a time near minimum solar activity. The mean solar modulation factor is 0.69¿0.04 at altitudes ranging from 10 to 20 km altitude. ¿ American Geophysical Union 1994