Originating within U.S. military defense networks, the Internet spread to international academic platforms and then to the public in the 1990s, greatly affecting the global economy, society, and culture. Due to the dot-com boom, stable monetary policy, and reduced social welfare spending, the 1990s saw the longest economic expansion in modern U.S. history. Beginning in 1994, the U.S. signed the North American Free Trade Agreement (NAFTA), causing trade among the U.S., Canada, and Mexico to soar.