Mercosur is the largest preferential trade agreement in Latin America. The four countries include Argentina, Brazil, Paraguay, and Uruguay. After the terrorist attacks of Sept. 11, 2001, ministers from the Mercusur countries agreed to reinvigorate the so-called Four Plus One Rose Garden Agreement of 1991 in order to strengthen trade ties between the Mercocur region and the United States. Working groups have been established in the areas of agricultural trade, industrial trade, investment development, and electronic commerce.