The formation and diapiric destruction of salt canopies have a direct impact on fluid flow and hydrocarbon migration in areas such as the Gulf of Mexico. Inferring the history and pattern of salt redistribution in even a local area can be time-consuming and is subject to uncertainties of many kinds. We demonstrate in this chapter that it is possible to infer the gross 3-D pattern of salt redistribution and the time when salt welds form directly from the sedimentation pattern and the present position of salt welds. The algorithm is based on the simple assumption that after isostatic adjustment is taken into account, accommodation space in areas with greater than average sediment loading is provided by salt movement to areas of less than average sediment loading. Although the algorithm is crude in several regards and could be improved by interpreter intervention, we show that the 2-D history of salt redistribution it estimates is almost identical to published salt migration histories inferred by conventional means in one test area. Applying the methods to a 20- 50-km area in the offshore Louisiana Gulf of Mexico, we find that the 3-D simulation estimates salt-weld formation at significantly later time in the Eugene Island Block 330 area (0.45 versus 1.3 Ma) than 2-D simulations. The later time is more compatible with geochemical indications of late filling for the Eugene Island Block 330 reservoirs. The estimated timing of salt-weld formation does not depend on the present thickness of salt. Modeling subsalt pore-water movement through microdarcy subsalt strata indicates that brines can be drawn to early-opening salt from distances of 50 km or more.