LOS ANGELES (AP) — A strike dramatically slowed activity at the ports of Los Angeles and Long Beach — the nation’s busiest cargo complex — despite renewed efforts to end the walkout.

Seven of eight terminals in Los Angeles and three of six in Long Beach were closed to cargo container traffic Friday, the fourth day of the walkout, as dockworkers refused to cross picket lines set up by union clerical workers who claim shippers are outsourcing their jobs.