Interior of a large sanitary sewer viewed from an access manhole. In the developed world, sewers are pipes from buildings to one or more levels of larger underground trunk mains, which transport the sewage to sewage treatment facilities.
Free trade is a policy followed by some international markets in which countries' governments do not restrict imports from, or exports to, other countries. Free trade is exemplified by the European Economic Area and the North American Free Trade Agreement, which have established open markets. Most nations are today members of the World Trade Organization (WTO) multilateral trade agreements.
What is the North American Free Trade Agreement? In January 1994, the United States, Mexico and Canada entered into the North American Free Trade Agreement (NAFTA), creating the largest free trade area and richest market in the world. The NAFTA is the most comprehensive regional trade agreement ever negotiated by the United States and is scheduled to be fully implemented by the year 2008. In 1996, U.S. two-way trade in goods under the NAFTA with Canada and Mexico stood at $420 billion--a 44 % increase since the NAFTA was signed.