A network of gravity base stations in the Mississippi Embayment was repeatedly occupied, beginning in November 1975, although the majority of the occupations were between Sepember 1976 and September 1978. Variations in the gravitational difference between most pairs of stations has a standard deviation of 15 μGal and may be attributed to random error. However, the gravitational difference between three station pairs exhibited a temporal change of approximately 45 μGal between the July and November 1977 surveys, while the difference between three other pairs changed by smaller and less statistically significant amounts. Neither observed changes in groundwater elevation nor regional tectonic activity, as indicated by seismicity, can explain the observed variations. The most probable source is a localized change in elevation caused by the surface loading associated with changes in stage of the Mississippi River.