Liberty Hill site in San Pedro, Los Angeles, California was the site of the 1923 strike by the Marine Transport Workers Industrial Union 510 a part of the Industrial Workers of the World (IWW).

The strike was called to draw attention to the worker's low wages and poor working conditions.

[1] The strike tied up 90 ships in Port of Los Angeles San Pedro.

[2][3] On May 15, 1923, writer Upton Sinclair spoke to approximately 3,000 striking longshoremen at Liberty Hill.

[4] The strike did not achieve its goal, but did start a movement that found success in the 1930s, the Congress of Industrial Organizations.