Hundreds of anti-Wall Street protesters have blocked gates and delayed lorries at three ports on the US West Coast.
The partial shutdown of harbours in California, Oregon and Washington states resulted in a handful of arrests, but no major clashes.
From early on Monday, activists picketed gates, beat drums and carried signs with slogans such as “Shut Down Wall St on the Waterfront”.
The rallies come a month after police dismantled Occupy camps across the US.