For reasons relating to disease prevalence and lack of sanitation, ancient Mesopotamian cities were likely characterized by a surfeit of deaths over births. This meant that over the long term such cities could only endure under conditions of sustained urban immigration. Available data is insufficient to accurately estimate the numbers of immigrants that ancient Mesopotamian urban centers would have needed on an annual basis in order to either maintain demographic equilibrium or grow. However, with important caveats, it may be possible to arrive at estimates of urban demographic deficits in ancient Mesopotamia by examining existing archaeological settlement pattern data from the area in light of data for the demographic dynamics of pre-modern cities in northern Europe in the 17th and 18th centuries ad. Below, a case study is presented illustrating the potential contribution of this comparative approach to understanding the dynamics of Mesopotamian urbanism at the very beginnings of the third millennium bc.