Superposed epoch analyses of a 46.5-year series of the geomagnetic activity indices Ap and of a 110-year series of the aa indices show a weekend increase in geomagnetic activity. A similar but not identical increase is observed in 12 years of Pc 1 geomagnetic pulsation occurrence data, and there is a matching decrease in a 7.5-year interval of VLF whistler--derived magnetospheric plasma densities. The increases in activity are not large, but standard statistical analyses of the data suggest that the increases are at least marginally significant, and the presence of the same increase in a variety of independent data also suggests that the 'weekend effect' is real. It is hypothesized that the increase of activity is related to a generally reduced level of power line harmonic radiation into the magnetosphere during weekends. Power usage data from Quebec show a repetitive weekend decrease and thus support part of this hypothesis.