Why do freeways affect spatial structure? We identify and quantify the local disamenity effects of freeways. Freeways cause slower growth in central neighborhoods (where local disamenities exceed regional accessibility benefits) compared with outlying neighborhoods (where access benefits exceed disamenities). A quantitative model calibrated to Chicago attributes one-third of the effect of freeways on central-city decline to reduced quality of life. Barrier effects are a major factor in the disamenity value of a freeway. Local disamenities from freeways, as opposed to their regional accessibility benefits, had large effects on the spatial structure of cities, suburbanization, and welfare.