The following is the June 14, 2018 Congressional Research Service report, Canada-U.S. Relations.
From the Report:
Relations between the United States and Canada traditionally have been close, bound together by a common 5,500-mile border—“the longest undefended border in the world”—as well as by shared history and values. The countries have long-standing mutual security commitments under the North Atlantic Treaty Organization (NATO) and North American Aerospace Defense Command (NORAD), and continue to work together to address international security challenges, such as the Islamic State insurgency in Iraq and Syria. Canada and the United States also maintain close intelligence and law enforcement ties and have engaged in a variety of initiatives to strengthen border security and cybersecurity in recent years.
Although Canada’s foreign and defense policies are usually in harmony with those of the United States, disagreements arise from time to time. Canada’s Liberal Party government, led by Prime Minister Justin Trudeau, has prioritized multilateral efforts to renew and strengthen the rules-based international order since coming to power in November 2015. It has expressed disappointment with President Donald Trump’s decisions to withdraw from international accords, such as the Paris Agreement on climate change, and has questioned whether the United States is abandoning its global leadership role. Such concerns have been heightened by the discord witnessed at the G-7 summit held at Charlevoix, Quebec, in June 2018.
The United States and Canada maintain extensive commercial ties, with total two-way cross-border goods and services trade amounting to over $1.6 billion per day in 2017. Bilateral trade relations have grown increasingly strained, however, as old irritants, such as softwood lumber trade, have reemerged, and the countries’ differing trade policy objectives have given rise to new disputes. Efforts to renegotiate the 1994 North America Free Trade Agreement (NAFTA) and the Trump Administration’s imposition of tariffs on Canadian steel and aluminum have proven particularly contentious.
Many Members of Congress follow U.S.-Canada issues that affect their states and districts, such as Great Lakes restoration efforts and ongoing negotiations over the Columbia River Treaty. Since Canada and the United States are similar in many ways, lawmakers in both countries also study solutions proposed across the border on such issues as federal fiscal policy and federal-provincial power sharing. U.S. and Canadian domestic policies have diverged on a variety of matters over the past year and a half, including taxation and environmental protection. This report presents an overview of Canada’s political situation, foreign and security policy, and economic and trade policy, focusing particularly on issues that may be relevant to U.S. policymakers.