International Brotherhood of Teamsters Local 70, of Oakland, California, was chartered in 1901. In 1901, Local 70 joined with its San Francisco counterpart, Local 85, and other Bay Area Teamster locals in organizing a central organization called the Team Drivers Joint Executive Council. After the 1906 earthquake and fire, Local 70 saw a rise in membership as San Francisco companies transferred operations to the East Bay. More work meant higher wages and more interest in unions. Also as a result of the fire, the Team Drivers Joint Executive Council was reorganized as San Francisco Bay Area Joint Council 7, with Local 70 as a member.

From 1920 to 1949, Local 70 was led by its dynamic and controversial secretary-treasurer, Charles W. Real (1888-1966). In 1935 Real gave his support to a plan, opposed by Local 85, to organize Bay Area highway delivery drivers. As a result, Local 70 gained several hundred new members. Real was expelled from Local 70 for unknown reasons in 1949.

In July 1934, Local 70 joined dozens of other unions up and down the Pacific coast in a sympathy strike after the events of "Bloody Thursday" in San Francisco. During the strike, Local 70 continued to help city and county officials supply food to the East Bay. In 1937, Local 70 joined approximately 150 other Teamster locals in eleven western states to form the Western Conference of Teamsters - a multi-jurisdictional regional body, unprecedented in Teamster history - led by Seattle Teamster Dave Beck. Beck subsequently rose to become president of the International Brotherhood of Teamsters in 1952.

In April 1937, Beck placed Local 70 in trusteeship for one year after Oakland Teamsters refused to cross the picket lines of longshoremen led by Harry Bridges. The trusteeship suspended Local 70's right of self-rule, ousted several officers, canceled all regular union meetings, and placed an outside agent (appointed by Beck) in temporary control. Beck then ordered Local 70 to break Bridges's strike. However, more than 500 of Local 70's 2200 members met secretly to vow allegiance to the ousted officers and to promise to honor the longshoremen's picket lines. On May 2, Beck himself spoke at a mass meeting for Oakland Teamsters where he garnered their compliance in return for $1 per day wage increases. Local 70 thereafter ignored the Bridges's picket lines, sparking a long-standing rivalry between Bay Area Teamsters and longshoremen.

Local 70 initiated three lengthy strikes in the early 1960s. Seeking higher wages and better fringe benefits, Local 70 went on strike in July 1961 against members of the Lumber and Mill Employers' Association and four ready-mixed concrete companies. The dispute was resolved in late September. Also in September 1961, Local 70 joined Teamsters Locals 896 (bottlers) and 278 (drivers) in a strike against several soft drink bottlers in San Francisco, Alameda, and San Mateo counties. In response, four soft drink companies purchased newspaper, radio, and newspaper advertisements to recruit strikebreakers in what the East Bay Labor Journal called the "most serious strikebreaking drive by employers in 25 years." The strike ended in October when Oakland mayor John C. Houlihan stepped in and helped settle the dispute. In November 1962, Local 70 initiated a wildcat strike against Consolidated Freightways after the company fired two Teamsters for refusing to unload a non-union trailer. The dispute lasted for almost a month. Consolidated Freightways fired all 126 of the striking union members and obtained a restraining order to stop their picketing. The dispute went before arbitrator Arthur M. Ross in December, who reinstated (with unimpaired senority but without back pay) all but five of the striking Teamsters.

In May 1964, Teamster Local 291, representing construction, excavation, ready-mix, and lumber drivers, split from Local 70.