Sue Ko Lee was a member of the Chinese Ladies' Garment Workers' Union. After working at the National Dollar Store/Golden Gate Manufacturing, Sue Ko Lee became a business agent at another garment factory, then secretary of the union local and the San Francisco Joint Board, as well as a delegate to the International Ladies' Garment Workers' Union national convention.

In the 1930s, the garment industry was the largest employer in San Francisco's Chinatown and employees worked in sweatshop conditions, earning low wages. In response to these conditions, the International Ladies' Garment Workers' Union (ILGWU) organized a campaign to keep work from flowing out of union shops to Chinese manufacturers and established the Chinese Ladies' Garment Workers' Union, Local 361 in 1937. Under the leadership of ILGWU organizer Jennie Matyas, a successful union election was won at the National Dollar Store factory for better wages in 1938. The owner, a prominent Chinatown businessman, quickly sold the facility to Golden Gate Manufacturing, a supposedly new company, headed by the factory manager and another former National Dollar Store employee. This supposed change of ownership allowed management to disregard the hard won contract. Seeing this move as an attempt to break the union, the workers went on strike, picketing the factory and its three retail stores in San Francisco for 15 weeks before the owner finally negotiated with the workers to settle a contract.