On the size and number of preferential trading arrangements

This paper uses a multi-country political economy model to investigate the possibility of achieving global free trade through the expansion of Preferential Trading Arrangements (PTAs). It is shown that bloc expansion would result in global free trade if blocs have an open membership. However, that would not be the case if membership were selective: at some point, the members of the bloc would stop accepting new members and this would lead to the creation of a second bloc. The likelihood of such a second bloc would make the members of the first bloc choose a larger bloc size than they would have chosen if only one bloc was allowed to form.