On July 1, 1867, the British North America Act officially took effect, creating the Dominion of Canada and fundamentally reshaping the map of North America. This pivotal moment united the provinces of New Brunswick, Nova Scotia, Ontario, and Quebec into a self-governing confederation, a milestone now celebrated annually as Canada Day. In this episode of Deep Dive, Peter Rowan and Noah Feldman explore the political mechanics behind this unification and its lasting impact on global governance. The conversation also shifts to celebrate three cultural giants born on this day: the humanitarian icon Princess Diana, the comedic powerhouse Dan Aykroyd, and the trailblazing Blondie frontwoman Debbie Harry. Finally, the episode examines a landmark moment in media history: the airing of the first American television commercial in 1941, a ten-second Bulova watch advertisement that cost a mere nine dollars and signaled the dawn of a new era in consumer marketing and workforce dynamics.