Following the considerable attention of activity-based models in transportation planning and forecasting, and the necessity to understand and reveal the impacts of transportation policies, this paper aims to simulate and examine a population policy scenario. It explicitly uses FEATHERS, a demand-side activity-based model, operational for Flanders, Belgium. The ABM is required to estimate how the interzonal migration of Flanders’ population from small towns/villages to large, urbanized city areas will closely affect the daily activity-travel choices of the individuals. A current baseline scenario is executed alongside three migration scenarios that account for a spatial redistribution of the population (2%, 5%, 10%) with equal proportions. Results suggest an impact on mode choice during peak hours, with a significant shift from car as a driver to public transport. Besides mode choice, there is a considerable decrease in the total number of trips. As a result, the total vehicle kilometres travelled, and total vehicle hours travelled reduce remarkably. While on the contrary there is hardly any effect on the activity choice.