Occupy Seattle protesters had started setting up wooden crates and aluminum in front of the entrance to Terminal 5 when police moved in to clear the area. Earlier, police reported "multiple" arrests at nearby Terminal 18 after about 100 occupy protesters stopped traffic for about 20 minutes.
The protests were part of a national effort to disrupt West Coast port traffic. The Seattle activity snarled nearby traffic during the Monday evening commute and caused several bus routes to be rerouted or delayed.
About 100 protesters blocked railroad tracks near downtown Bellingham. Some were seen lying down, bound together by bicycle locks around their necks.
A train expected at 3 p.m. was delayed by Burlington Northern Santa Fe as police arrested protesters who refused to clear the tracks.
Earlier in the longshoremen at the Longview port went home for the day, essentially shutting down the terminal after an Occupy Wall Street demonstration.
Protesters are most upset by two West Coast companies: port operator SSA Marine and grain exporter EGT. The bank, Goldman Sachs, manages an investment fund that holds a minority stake in SSA Marine and has been a frequent target of protesters.
They say they are standing up for workers against the port companies, which have had high-profile clashes with union workers lately. Longshoremen at the Port of Longview, for example, have had a longstanding dispute with EGT.
A spokesman for SSA Marine said the company is a union shop and is the largest employer of ILWU workers on the U.S. West Coast.
Several hundred people began picketing at the Port of Oakland before dawn and blocked some trucks from going inside. Police are monitoring at the scene, but no major clashes have been reported so far. Occupy protesters successfully shut down the port in November.
In Los Angeles, Occupy LA protesters have ended a demonstration at one of the world's largest port complexes after briefly blocking traffic. Only one arrest was reported as about 200 demonstrators gathered Monday morning near a shipping terminal at the Port of Long Beach.
Police forced the demonstrators out of a parking lot but several dozen regrouped and briefly blocked a major roadway, backing up a line of trucks heading to the port. Heavy rain dampened the protest and the demonstrators, who were flanked by dozens of police, have now moved off, effectively making a peaceful end to a four-hour protest.
Port spokesman John Pope says other routes are available and disruption has been minimal.
In Vancouver, B.C., police say Occupy Wall Street demonstrators briefly blocked two gates at Port Metro Vancouver near downtown Vancouver. The Canadian Press reported demonstrators held up a large banner proclaiming solidarity with Longshore union members involved in a dispute at the Port of Longview, Wash.
The disruption lasted for about an hour before the protest moved to a second gate, blocking it for less than 30 minutes before moving on.
Down in Portland, About 300 protesters from Occupy Portland blocked entrances to two terminals at the Port of Portland, preventing trucks from entering.
The Oregonian said workers at the two terminals were told to stay home on Monday. Spokesman Josh Thomas said an unspecified number of workers at the terminals wouldn't be paid. A couple of hundred people gathered at the port Monday morning to try to shut down the port's terminals. Police in riot gear were on hand, but there were no confrontations or arrests.
Before the protest began, police arrested three people on their way to the protest. In one case, the police seized a gun, ammunition clips and a sword. A spokeswoman for Occupy Portland said they weren't part of the group.
The protests being billed as action against "Wall Street on the waterfront" are perhaps the Occupy movement's most dramatic gesture since police raids sent most remaining camps scattering last month. Demonstrators began forming those camps around the country about two months ago to protest what they call corporate greed and economic inequality.
Officials at West Coast ports said they have been coordinating with law enforcement agencies as they prepare for possible disruptions. Protesters said police violence against blockades in any city will trigger an extension of blockades in other cities as a show of resolve.
Organizers of the port demonstrations said they hope to draw thousands to stand in solidarity with longshoremen and port truckers they said are being exploited, though the International Longshore and Warehouse Union, which represents many thousands of longshoremen up and down the West Coast, has distanced itself from the shutdown effort.
The union's president suggested in a letter to members that protesters were attempting to co-opt the union's cause to advance their own agenda.
Protesters have cited a longstanding dispute between longshoremen at the Port of Longview in Washington and grain exporter EGT as a key reason for the blockades. Shutdown supporters said they're not asking longshoremen to organize a work stoppage in violation of their contract but simply asking them to exercise their free speech rights and stay off the job, in keeping with the union's historic tradition of activism.
If protesters muster large enough numbers to block port entrances, arbitrators could declare unsafe working conditions, which would allow port workers to stay home.
Organized labor appears divided over the port shutdown effort. In Oakland, which saw strong union support for the Nov. 2 general strike that culminated in the closing of the port, the city's teachers union is backing Monday's action, while the county's construction workers have come out against the shutdown, saying the port has provided jobs to many unemployed workers and apprentices.