Natural gas markets in the Southern Cone present similarities that can be better exploited under regional integration. The region has both large reserves and the correspondingly-large potential domestic markets necessary to justify the major costs involved in developing those reserves and in building the network infrastructure. With the exception of Argentina, natural gas markets in the Southern Cone started to develop relatively recently, based on important discoveries of this hydrocarbon in the late 1980s and early 1990s. By 2006, proved natural gas reserves in the Southern Cone reached 57,841 bcf, or about 1% of the world's total. However, the dynamics of natural gas reserves differ considerably across countries. Data on the proven natural gas reserves in the Southern Cone from 1990 to 2006 showed that proven reserves increased sharply in Bolivia and Brazil while they decreased in Argentina and Chile. In addition, between 1990 and 2006 natural gas demand in the region increased steadily, continuing its upward trend even in years of economic recession. Gas consumption increased much faster than GDP in all countries, though at a different pace. It increased about 30%/yr more rapidly than GDP in Argentina, twice as fast in Bolivia, Brazil, and Chile, and even more quickly in Uruguay. Gas trade in the Southern Cone has increased considerably in the last decade, but the region is still far away from regional integration. The degree of physical infrastructure integration moves from isolated national systems to operation of a fully-integrated regional system.