Although there have been a small number of empirical studies that examine northbound border crossings between Mexico and the United States, very few examine the potential impacts of both tolls and exchange rates on the various traffic categories.  This effort attempts to partially fill that gap in the applied economics literature by modeling northbound traffic flows at one of the largest regional economies along the border.  Results indicate that business cycle fluctuations, variations in the real exchange rate, and changes in real toll tariffs all influence border crossings.  The results also indicate that real toll rates may play less of a role than might be expected.