The 1934 West Coast waterfront strike encouraged organizing drives among warehouse workers in San Francisco, with the support of longshoremen who recognized that unionizing warehouse workers who worked in close proximity to themselves could protect longshore labor standards and prevent the use of non-union laborers as strikebreakers. In what has been called the "march inland," unionization of warehouse workers spread rapidly throughout Northern California from 1934-1938, an effort which pit the West Coast longshore union against the International Brotherhood of Teamsters (IBT) in jurisdictional disputes over the inland warehouse workers. When the AFL sided the the Teamsters, the San Francisco locals voted to separate from the ILA in 1937 and formed the International Longshoremen’s and Warehousemen’s Union (ILWU), affiliated under the Congress of Industrial Organizations (CIO). The ILWU became a union of longshoremen and warehouse workers under the leadership of militant longshoreman Harry Bridges. That same year the Weighers, Warehousemen’s and Cereal Workers Union Local 38-44 in San Francisco became ILWU Local 6.