Stress-induced voiding is an important reliability concern in narrow aluminum based metallizations used as interconnects in very large scale integrated circuits. The thermal stresses that arise in the interconnects after excursions to elevated temperatures are tensile and extremely high. Void nucleation is commonly found to take place at the line edges where the stress is highest. In lines of rectangular cross section, in particular, there arise shear stresses at line edges and corners which can be higher than the dilational stress components. In this paper we consider analytically the stress states arising in interconnect lines of rectangular cross section. We argue that void nucleation is likely to be connected to the high shear stress at the edges and corners, facilitating grain boundary sliding.