This paper considers some of the Canadian scientific and political responses to the International Geophysical Year (IGY) 1957–1958. Histories of the IGY have hitherto often concentrated on scientific activity in Antarctica and advances in satellite technology, made manifest in the Soviet launch of Sputnik. Such histories hint at a contradiction at the heart of the IGY – attempts at international scientific cooperation were always concurrent with cold war national rivalries. These tensions were not limited to the superpowers and the IGY helped focus scientific competition between other national polities, including Canada. By examining the circumstances surrounding the creation of the Government of Canada’s Polar Continental Shelf Project in April 1958, the paper investigates attempts to mobilize a pan-Canadian nationalism in response to perceived American and Soviet incursions upon territorial sovereignty during the IGY. The PCSP’s ostensible purpose was to collect geophysical data for US satellite launch tests in the Canadian High Arctic. However, by placing the founding of the PCSP within the political context of the First UN Conference on the Law of the Sea in 1958, and the unprecedented electoral success of the Progressive Conservatives across Canada during the same year, the paper develops a more sensitive appreciation of the complicated historical geographies of the IGY.