Southwest Marine is the last remaining example of the once highly significant shipbuilding industry at the Port of Los Angeles.

The original shipyard is remarkably intact dating to World War II, with sixteen buildings and structures considered contributing elements of a National Register-eligible historic district.

The site was first developed for shipbuilding in 1918 by Southwestern Shipbuilding, which was under contract to provide the government with merchant vessels as part of the Shipping Act of 1916. The company set world speed records for delivering ships to the government and employed 8,600 people in 1919. 

By 1922, the site had been acquired by Bethlehem Shipbuilding Corporation, marking an East Coast company’s investment in the growth of Los Angeles Harbor. During World War II, the Bethlehem Shipyard built approximately 40 destroyers and employed 6,000 workers at the height of production. In addition to serving as an excellent plant for wartime production, it repaired and returned nearly two Navy vessels a day. 

After the war, Bethlehem transitioned to ship repair and Navy oil tanker storage. In 1981, Bethlehem Steel sold the property to Southwest Marine, which continued ship-related activities at the site. 

In addition to its significance to Los Angeles’ shipbuilding industry, Southwest Marine is a popular filming location and has served as the setting for television series including 24, True Blood, Dexter, CSI: Crime Scene Investigation, and Entourage, and the films Spider-Man, Charlie's Angels, Live Free or Die Hard, and Mr. and Mrs. Smith, among many others.

Due to a recent realignment of Seaside Avenue, the Southwest Marine Terminal Administrative Building, a contributing structure in the National Register-eligible Bethlehem Shipyard Historic District, now stands in the parking lot of the Al Larson Boat Shop Complex. It is currently vacant.

The following buildings at the Southwest Marine terminal complex have been identified as contributing elements of a National Register-eligible historic district:

• Administration Building (1941)
• Medical Building (1941, expanded in 1941)
• Foreman’s Building (1941)
• Transportation Shop (1941)
• Blacksmith and Anglesmith Shop (1918, reconfigured in 1941)
• Plate Shop (1918, reconfigured in 1941)
• Machine Shop (1941)
• Machine Storage and Warehouse Building (1941, expanded in 1943)
• Shop Building (1941)
• Employee’s Building (1941)
• Paint Shop and Substation (ca. 1940)
• Substation No. 3 (1918)
• Substation No. 7 (1918, expanded in 1941)
• Building No. 22 (1941)
• Dry Dock No. 2 (1919)
• Cranes (1918-1946)

The Conservancy has worked for over six years to prevent the demolition of the Southwest Marine Shipyard historic district.

Proposed for demolition by the Port of Los Angeles in 2006, the World War II-era shipyard has more recently been threatened with having its slips filled in with contaminated dredge spoils as part of a Port project to deepen the main channel.

In 2011, a two-year effort to reopen Southwest Marine as a shipbuilding and repair facility was rejected by the Port of Los Angeles and the Los Angeles City Council. Now the two remaining slips are being filled with dredge material from an ongoing channel deepening project.