A Guide to the United States’ History of Recognition, Diplomatic, and Consular Relations, by Country, since 1776: Canada
The Dominion of Canada formed in 1867, but as an integral part of the British Empire its foreign relations remained under the control of London. Over the next six decades Canada gradually won greater control over its external affairs, spurred in part by the demands of managing its relationship with the United States. American and Canadian government officials increasingly interacted through joint commissions and military cooperation, and the two governments even negotiated a bilateral fisheries treaty in 1923. It was not until 1926, however, that the United Kingdom acknowledged that Canada was fully autonomous in the conduct of its foreign affairs.
U.S. Recognition of Canadian Independence, 1927.
The United States recognized Canada as an independent state with autonomous control over its foreign relations on February 18, 1927, when Vincent Massey presented his credentials in Washington as Canadian Envoy Extraordinary and Minister Plenipotentiary. This action followed the 1926 British Imperial Conference that produced the Balfour Declaration, which stated the United Kingdom and the Dominions “are autonomous Communities within the British Empire, equal in status, in no way subordinate one to another in any aspect of their domestic or external affairs.”
Establishment of Diplomatic Relations, 1927.
Diplomatic relations were established on February 18, 1927, when Vincent Massey presented his credentials in Washington as Canadian Envoy Extraordinary and Minister Plenipotentiary.