This paper assesses whether the disruption of world trade, protectionist policies and industrial growth that dominated South American economic history from 1912 to 1950 permitted an increase in intraregional trade. The paper demonstrates that during this period intraregional trade reached some of the highest levels of the entire 20th century. These levels have since receded. With the exception of some Brazilian exports, most of intraregional trade had the same features as global trade during this period: a high concentration on few products of very low value-added.