Along the northern coastal boundary of the Mid-Atlantic Bight, synthetic subsurface pressure records derived from 1975 tide gage and airway weather observations are examined for fluctuations having monthly time scales. Additional calculations are performed to determine the factors controlling variance in these pressure data. Similar analyses are applied to the longshore gradient in synthetic subsurface pressure. Results of the study indicate that synthetic subsurface pressures are controlled by three mechanisms, two each at either end of the coastal segment. Fluctuations in Gulf Stream position have a significant effect on monthly mean pressures, which are uniform along the coast. At the western end of the coastal segment, east-west winds are also important, while changes in water density contribute significantly in subsurface pressure variance at the eastern end. Coastal steric differences are found to be a minor contributor to monthly fluctuations of longshore pressure gradient, while the coastal mean east-west winds effect a linear response in the gradient. Using this relationship and upon removal of geodetic leveling errors, the annual mean longshore sea surface slope is calculated to be 1.6¿10-7, forming a westward pressure gradient along the northern boundary of the Mid-Atlantic Bight.