A full US trade embargo would immediately cut off ~70% of Canadian goods exports (energy, autos, manufacturing) plus key imports, likely shrinking GDP 15-25%+ in year one via lost markets and supply-chain collapse. Tech bans would cripple cloud (US firms hold ~85%), software and AI. Credit-card bans (Visa/MC dominate) and US banking/SWIFT cutoff would freeze payments, trade finance and capital flows, triggering banking stress, CAD crash, shortages and mass unemployment. Recovery via diversification would take years amid severe disruption.