When Shocks Are Permanent: Port Congestion-Induced Hysteresis in Maritime Disruptions - Evidence from COVID-19, Suez, and Red Sea Crises

This paper quantifies how shocks at strategic maritime chokepoints propagate into global trade frictions, and when “temporary” disruptions become persistent through port-congestion hysteresis. Using high-frequency PortWatch IMF data, this study analyzes 70,728 observations across eight major chokepoints spanning 2019–2025, covering three structurally distinct disruptions: the COVID-19 demand shock, the Ever Given–induced Suez blockage, and the Red Sea security crisis. The empirical strategy combines difference-in-differences (with event-study dynamics), interrupted time-series segmented regression for recovery trajectories, and state-dependent interaction models that allow treatment effects to vary with pre-shock capacity utilisation and vessel composition. Results indicate sharp heterogeneity by shock type and cargo: COVID-19 reduces daily traffic by 16.5% and capacity by 15.9%, with container flows falling 2.8× more than dry bulk; the Suez blockage generates a sizeable but short-lived decline (≈ 7.2%) with limited persistence; and the Red Sea crisis produces a sustained contraction (≈ 3.1%) alongside route substitution. Crucially, highly utilised chokepoints recover materially more slowly (≈ 73% longer recovery windows), implying partial hysteresis, with aggregate traffic in 2024–2025 remaining below 2019 baselines. Policy implications are direct: resilience hinges on maintaining “surge” capacity at congested hubs, investing in scalable alternatives, and embedding utilisation-triggered contingency protocols into maritime governance. JEL Classifications: C23, D62, F14, F17, R41