In the early 1930s, the International Longshoremen's Association, led by San Francisco-based Harry Bridges, tried to unionize all West Coast dockworkers to improve pay and working conditions. In 1934, after employers refused to recognize the union, West Coast longshoremen went out on strike for 98 days, seriously disrupting trade. At Seattle's Smith Cove, picketing strikers blocked access to the piers and tried to prevent ships from being loaded and unloaded. The mayor called out the police to curb periodic violence.

Strikers and sympathizers had stormed Seattle's police headquarters after police raids on Communist and radical unions began on July 18. When the men retreated to Smith Cove to join the picketers, Mayor Charles Smith led 300 policemen to the area armed with tear gas and submachine guns. Injuries were heavy on both sides, but no shots were fired.

Caption from June 22, 1934 Seattle Post-Intelligencer: [There was a] clash between mounted police and striking longshoremen yesterday afternoon near the entrance to Pier 40. With riot clubs ready for action, the mounted officers are shown riding into the crowd of milling pickets. Three men were injured in the melee. In the left foreground, one of the injured men is shown being assisted from the scene by one of his fellow strikers. The clash resulted when the strikers blocked the tracks to prevent the locomotive shown in the background from entering the pier.

Caption on sleeve: Strikes - 1934 - Longshore.