Urban sprawl in mid-size Latin American cities, like Concepción in Chile, has increased significantly from 1990 to 2009. The city has expanded by 96%, with new urban areas forming a central core and less dense sub-centers following transportation routes. The distance between these areas has grown by 2 km, and the urbanized surfaces have become more irregular and less compact. The findings show a nearly 100% increase in urban surface, the importance of a polycentric urban structure, and the growing morphological irregularity of the sprawl.