 The estimate and trends are also consistent with figures reported by the Center for Migration Studies, which reported that the U.S. illegal immigrant population fell to 10.9 million by January 2016, the lowest number since 2003.A 2018 paper by three Yale School of Management professors estimated that the illegal immigrant population was in the range of 16 million to 29 million, however the methodology presented in this study has been criticized as leading to vastly overstated results.The "residual method" is widely used to estimate the illegal immigrant population of the US.