Both 42- and 76-Hz horizontal magnetic field strength measurements were made in Connecticut during 1974. These measurements are for the purpose of further investigating sunrise, daytime, sunset, nighttime, and seasonal ELF propagation variations. The transmission source for these 1.6-Mm range measurements was the U.S. Navy ELF Wisconsin Test Facility (WTF). The principal results obtained from these measurements were (1) ELF nighttime propagation is much more variable than daytime propagation, (2) the 'Halloween effect' was observed for the fifth year in a row, and (3) there may be as many as 80 nights each year when the average nighttime field strength will be approximately 3 dB lower than on the preceding or following nights.