1993. It includes Canada, the United States, and Mexico, with a combined population of 450 million and an economy of over $20.8 trillion.
I believe that this is a fantastic example of keeping tensions low between 3 neighboring nations who share different cultural values. In this example, NAFTA allowed for the U.S., Mexico, and Canada, to both work together in terms of trade, rather than compete with one another in the North American theatre. If we hadn't had North American trade between the 3 countries, than the U.S. would never have the chance to produce cars in Mexico, giving Mexico more jobs and wealth within their economy, which in turn helps the U.S.