The Port of San Francisco was once the largest and busiest seaport on the West Coast. It featured rows of piers perpendicular to the shore, where cargo from the moored ships was handled by cranes and manual labor and transported to nearby warehouses. The port handled cargo to and from trans-Pacific and Atlantic destinations, and was the West Coast center of the lumber trade. The 1934 West Coast Longshore Strike, an important episode in the history of the American labor movement, brought most ports to a standstill. The advent of container shipping made pier-based ports obsolete, and most commercial berths moved to the Port of Oakland and Port of Richmond. A few active berths specializing in break bulk cargo remain alongside the Islais Creek Channel.