In this paper we discuss the distribution of drag force along aligned arrays of cubes of different packing density. The distribution is evaluated via wind tunnel measurements performed on individual cubes located along the middle column of the array using a balance provided by a standard load cell. Results are compared with the drag force estimated by a pressure-derived method and clearly show a change of the distribution of the drag force. The force is uniform at low packing densities, while mostly acting on first rows of the arrays at large packing densities. This work leaves room for research tailored to a better parameterization of urban effects in dispersion models.