Automotive Machinist Lodge (AMU) No. 1305, a local lodge of the International Association of Machinists (IAM), obtained its charter on June 24th 1919. Local No. 1305 was originally based in San Francisco, first at 107 Valencia and then at 1750 Market Street, until it moved in 1988 to the current location at 150 South Blvd., San Mateo. Unfortunately no printed history of the AMU Local No. 1305 exists, but for a more general account of the IAM see Mark Perlman's The Machinists; a New Study in American Trade Unionism (1961). Richard Prime Boyden's unpublished thesis The San Francisco Machinists from Depression to Cold War 1930-1950, provides an account of machinists in the Bay Area.

The IAM was organized in Atlanta, Georgia in 1888 and principally centered on metal fabrication workers, initially representing skilled craftsmen who had completed a four year apprenticeship. AMU Lodge No. 1305 chartered a little over thirty years later and differed from the existing San Francisco machinist lodges in that it was primarily established to serve the needs of auto mechanics. The charter of 1919 marks the founding of what was then known as the Auto Mechanic Lodge No. 1305. A survey of the membership applications for the same year shows the candidates were young men in the auto and truck repair trade. Twenty years later although truck and car mechanics still accounted for the bulk of members, AMU Lodge No. 1305 also represented a diverse range of workers from bakery and brewery employees to mechanics employed on the maintenance of stevedoring machinery. The lodge during this period used both terms "Auto Mechanic Union, Lodge No. 1305" and "Automotive Machinist Union, Lodge No. 1305". Gradually the former name appears to have fallen into disuse as membership continued to diversify.

The labor conditions peculiar to the war years influenced membership patterns in AMU Lodge No. 1305. The most significant change was the admission of the first women members. Their entry was eased by changes in IAM policies during the 1930s when the recruitment policy was widened to include factory workers. These 'production workers' did not have a four year apprenticeship and tended to be proficient in only a few procedures. Similarly, during World War II women who had not undergone the four year apprenticeship were admitted to Lodge No. 1305 as 'specialists' or 'helpers'. Prior to World War II, women were only encouraged to join the AMU Lodge No. 1305 sister lodge, Golden West Ladies Auxiliary No. 125, which was established in 1940. The goal of the ladies auxiliary was to "bring within the folds of our organization every wife, mother, sister and daughter". The Ladies Auxiliary was involved in social activities and also provided Lodge No. 1305 machinists with financial and moral support in times of industrial strife.

In the post war years trade jurisdiction for Lodge No. 1305 covered an array of moving equipment (forklifts, buses, automobiles, container carriers, lifts and cranes) vital to industries ranging from car rental to container shipping. Lodge No. 1305 also represented the City and County automotive workers of San Francisco, Golden Gate Ferries, Golden Gate Bridge and Golden Gate Transit. In 1956 the AMU Lodge No. 1305 successfully sued the city in the Martin shop case which challenged the legality of the city's pay scales and vacation terms. The major employers of union members besides the city and county of San Francisco included Greyhound, UPS and Matson Terminal in Oakland. The geographic catchment area of Lodge No. 1305 was San Francisco, Eureka, Marin County and Oakland.

The history of a number of San Francisco and Bay Area machinist Lodges are interwoven with that of Lodge No. 1305 through merger or as a result of Lodge No. 1305 organizing. For instance, AMU Lodge No. 1305 organized Peninsula Auto Mechanics Lodge, AMU Lodge No. 1414. This local, chartered on June 9th 1936, was originally located in Redwood city before it moved in 1956 to San Mateo to share an office with local No. 1305. Similarly AMU Lodge No. 1305 organized Lodge No. 1101 of San Jose. By the mid 1970s Lodge No. 1305 had absorbed the automotive units of Lodge No. 238, a mixed local. In employer association agreements negotiated during World War II Lodge No. 1546, East Bay Automotive Machinist Lodge often acted in conjunction with Lodge No. 1305 and Lodge No. 1414.

Unlike other Bay Area machinist locals, such as the militant Lodge No. 284 in Oakland and Lodge No. 68 of San Francisco, AMU Lodge No. 1305 enjoyed peaceful relations with the Grand Lodge and in the war years especially, good relations with Bay Area employers. Notable events and achievements over the years include the elimination of piece work in the late 1930s, the 1965 motor car dealer strike and the 1969 Greyhound Strike. The Greyhound strike occurred in the summer of 1969 and involved three San Francisco locals, AMU No. 1305, IBT No. 665 and IBT No. 241. The AMU local No. 1305 was also involved in San Francisco politics including the election campaign for Harvey Milk

Over the years AMU Lodge No. 1305 has been affiliated with the following organizations: California Conference of Machinists, Northern California Machinists Automotive Trades District 190, Marin Labor Council, San Francisco Labor Council, California Federation of Labor and San Francisco Automotive Trade Council. Lodge No. 1305 also enjoyed close cooperation with San Francisco and East Bay Teamster locals, in particular, The International Brotherhood of Teamsters (IBT) Local No. 665, Garage and Service Station Employees and Local IBT No. 241.