Past work has shown that the interannual wind stress curl in the North Atlantic generates Rossby waves that reach the eastern U.S. coast and affect coastal sea level both there and along the northern coast of the Gulf of Mexico. Tide gauge and TOPEX/Poseidon satellite sea level height measurements show that this interannual signal penetrates all the way around the Gulf of Mexico shelf to the Yucatan Peninsula, with local alongshore interannual wind stress increasing the signal amplitude between Pensacola and the Texas-Louisiana shelf. Satellite observations show the seaward spatial structure of the sea level and the associated geostrophic flow. In theory this flow should depend on the angle $theta$ of the shelf edge with respect to due north and the Loop Current mean shelf edge flow. Off the northern boundary ($theta$ ≈ 90¿), in agreement with theory, the signal behaves as a coastal Kelvin wave, the sea level amplitude falling quickly away from the shelf edge with first baroclinic radius of deformation scale. Off the western boundary ($theta$ ≈ 180¿) the interannual sea level amplitude falls rapidly seaward of the shelf edge, consistent with short western boundary scales. However, off the eastern boundary ($theta$ small) formed by the west coast of Florida, the fall in interannual sea level amplitude seaward of the shelf edge is inconsistent with long Rossby wave theory. Interannual geostrophic Gulf of Mexico shelf edge flows may reach amplitudes of the order of 10 cm s-1, but along shelf flow amplitudes are a few centimeters per second or less. Even so, weak shelf flows of interannual frequency can transport particles many hundreds of kilometers.