The United States and Canada share more than a common border. Many people who live on the border live and work in both countries. People often travel freely between the two nations; the two nations are important to each other in terms of tourism as well. Canadian sports teams, such as the Toronto Raptors, play in American leagues. The two nations trade freely with each other through the North American Free Trade Agreement (NAFTA). The two nations share the English language and a common history of being British colonies.
The two nations have also fought together overseas. Canadian forces were present in World War I, World War II, and the Global War on Terrorism. While the United States does project its force more often than Canada, Canada is also a part of NATO and has sent troops when asked to do so. The United States and Canada share a very close relationship as well as a long border. This is probably one of the most important US diplomatic and economic relationships.