How much do disruptions to U.S.-bound shipping routes matter for the U.S. economy? A lot, and far more than conventional trade models suggest. To make this point, I just circulated a new paper, “Shipping to America,” with my dear coauthors Xiwen Bai, @YiliangLi_, @RicardoVMarto, and Francesco Zanetti: sas.upenn.edu/~jesusfv/Shipp… Using satellite vessel-tracking data, we build route-level measures of potential and effective capacity for all U.S.-bound container ships from 2016 to 2025. In recent supply disruptions, utilization losses ran 20 to 40 percentage points, and they began months before port congestion became visible. That is a lot. We then embed these measures in a general equilibrium model in which shipping firms reallocate a common fleet across routes, price above marginal cost, and ignore the congestion they create, while importers shift their sourcing in response to route profitability. The key result is that the reallocation triggered by a disruption has first-order welfare effects, so a route’s Domar weight is not a sufficient statistic for its welfare cost. Here we depart from conventional models, where some form of Hulten’s theorem holds and the welfare costs of supply disruptions are often small. But what I find most interesting is that the model lets us measure the economic value of military operations that keep sea lanes open. The 2023–2024 Red Sea attacks cost 0.35% of US output. Combining data on the cost of the U.S. Navy’s protection of Red Sea shipping with the model, we estimate that the Navy’s intervention delivered benefits of 0.04–0.08% of US output at a fiscal cost of 0.02%. While the Navy did not fully reopen the Red Sea, it cut the losses by a tenth to a quarter. The operation paid for itself two to four times over. The figure shows how we can track these operations: it plots the movements of the Arleigh Burke-class guided-missile destroyer USS Gravely (DDG 107) from AIS data. Because U.S. Navy ships usually switch off AIS during active operations, the data are sparse and cluster around the ship’s departures for operations and its returns to port. The punchline is clear: freedom of navigation is of the utmost strategic importance for the U.S. It has been so for every thalassocracy: Athens, Carthage, Venice, the Dutch Republic, Britain, and now the U.S. Let us not forget it.