求一篇英文文章,简单介绍美国和加拿大关系!

America and CanadaRelations between Canada and the United States have spanned more than two centuries。This includes a shared British colonial heritage,warfare during the 1770s and 1812,and the eventual development of one of the most successful international relationships in the modern world。Each is the other's chief economic partner and large-scale tourism and migration between the two nations has increased the similarities。The most serious breach in the relationship was the War of 1812,which saw an American invasion of then British North America and counter-invasions from British-Canadian forces。The border was demilitarized after the war and,apart from minor raids,has remained peaceful。Military collaboration began during World War II and continued throughout the Cold War on both a bilateral basis through NORAD and through multilateral participation in NATO。A high volume of trade and migration between the United States and Canada has generated closer ties,especially after the signing of the Canada – United States Free Trade Agreement in 1988。The two countries work closely to resolve trans-border environmental issues,an area of increasing importance in the bilateral relationship。