Although the olfactory receptor neurons converging onto the same glomeruli in the olfactory bulb are known, evidence for an olfactory map at cortical level is lacking. The current study finds that mitral cells that are born later during embryogenesis preferentially project to the olfactory tubercles as the late-born mitral cells tangentially migrate further on the axons of earlier born cells, forming an organization of neuronal projection into the olfactory cortex based on the timing of cell birth.