Until the spring of 2020, global commerce functioned like a finely tuned machine consisting of thousands if not millions of gears, all meshing in perfect sequence. A cargo ship leaving China on a two-week voyage could be timed within 30 minutes to dock in Los Angeles to offload its containers. Prescheduled trucks and trains would be waiting to carry containers to their destinations. Factories and warehouses had their inventories calculated to minimize storage costs by ensuring parts went straight into production and products spent minimal time on warehouse shelves. Airlines could reliably match pilots, crew and maintenance personnel with scheduled flights to keep passengers moving within tightly predicted time frames.