>What specifically caused this sudden spike over the last 3 months? Looks like it's because ships are leaving empty for China so the unloading has slowed since

>What specifically caused this sudden spike over the last 3 months? Looks like it's because ships are leaving empty for China so the unloading has slowed since the available warehouse space is taken up by outbound shipments (which are not being loaded because of that mismatch in shipping rates): However, westbound freight rates have not risen nearly as much, leading to an odd and problematic phenomenon: incentives for container owners to move them back to China empty to accelerate receipt of eastbound freight rates, instead of waiting for containers to be refilled to earn westbound freight rates as well. This is illustrated in the fourth chart which shows departing containers from LA/LB: a lot of them started leaving empty once eastbound freight rates surged. This further exacerbates supply chain issues, since US goods (i.e., grains) that were supposed to depart US railcars and warehouses for export remain in place, occupying space that US imported goods were destined for.