The Hyde Park Declaration | The Brian Mulroney Institute of Government

The following policy document is of former Prime Minister of Canada, the Right Hon. W. L. Mackenzie King's statement on the Hyde Park Declaration to the House of Commons one week after the declaration was signed by PM King and President Roosevelt.
The Hyde Park Declaration was signed by U.S. President Franklin D. Roosevelt and Canadian Prime Minister Mackenzie King on April 20, 1941, and it became one of the most significant economic agreements reached between Canada and the United States during the Second World War.
This came after the US passed the Lend-Lease Act, which was a policy that would allow for the production of war materials (and war aid) for the Allied countries as needed, with payment made at a later date.
PM Mackenzie King feared that the Lend-Lease Act may divert all British war orders from Canada to the US, so PM King and President Roosevelt signed the Hyde Park Declaration.
The Declaration outlined that American-produced war material manufactured in Canada would be included in the Lend-Lease Act, which would alleviate Canada's trade deficit and make it easier for Canada to meet Britain's demands and guarantee their financing.
Not only was this beneficial for war efforts, but PM Mackenzie King regarded the Hyde Park Declaration as a significant milestone in the Canada-US economic relationship.

Citation

Canada. Canada and the War. The Hyde Park Declaration: Cooperation in Economic Defence. Statement by Right Hon. W. L. Mackenzie King. [Ottawa, ON]: House of Commons, 1941. https://www.lipad.ca/full/1941/04/28/1/