Hillman found work there as an employee of Hart, Schaffner & Marx, a prominent manufacturer of men's clothing. When a spontaneous strike by a handful of women workers there led to a citywide strike of 45,000 garment workers in 1910, Hillman was a rank-and-file leader in the strike.
That strike was a bitter one and pitted the strikers against not only their employers and the local authorities, but also their own union, the United Garment Workers, a conservative AFL affiliate. When the UGW accepted an inadequate settlement, the membership rejected the offer and continued the strike, winning some gains at Hart, Schaffner. Hillman became a business agent for the new local.
The leadership of the international union mistrusted the more militant local leadership in Chicago and in other large urban locals, which had strong Socialist loyalties. When it tried to disenfranchise those locals' members at the UGW's 1914 convention, those locals, representing two thirds of the union's membership, bolted to form the Amalgamated Clothing Workers of America.
Hillman had taken the position of Chief Clerk within the International Ladies' Garment Workers' Union in New York in early 1914. He found that job, in which he tried to maintain the stability imposed on a ferociously competitive industry by the Protocols of Peace, and in which the internal rivalries within the union threatened to flare up into all-out conflict, frustrating. When the insurgents who had walked out of the UGW convention to form the Amalgamated sent him a telegram imploring him to accept the Presidency—followed by another telegram from Bessie Abramowitz, one of the original leaders of the 1910 strike, an important figure in union politics and his fiance—he accepted and left the ILG after less than a year.
Hillman knew the risks he was taking. The AFL refused to recognize the new union and the UGW regularly raided it, furnishing strikebreakers and signing contracts with struck employers, in the years to come. He helped the Amalgamated solidify its gains and extend its power in Chicago through a series of strikes in the last half of the 1910s and to extend the union's membership into important garment centers in Baltimore and Rochester, New York, where the union had to overcome divisions within garment workers on ethnic lines and the opposition of the Industrial Workers of the World.
The ACWA also benefited from the relatively pro-union stance of the federal government during World War I, during which the federal Board of Control and Labor Standards for Army Clothing enforced a policy of labor peace in return for union recognition. Hillman was particularly receptive to the opportunities that government intervention in labor relations presented the union; he not only did not have the ingrained distrust of governmental regulation that now marked Samuel Gompers and other leaders of the AFL, but had a firm belief in the sort of industrial democracy in which government helped mediate between labor and management. The government's interest in maintaining production and avoiding disruptive strikes helped the Amalgamated organize non-union outposts such as Rochester and control the cutthroat competition that had prevailed in the industry for decades.
That policy ended in 1919, when employers in nearly every industry with a history of unionism went on the offensive. The ACWA not only survived a four month lockout in New York City in 1919, but came away in an even stronger position. By 1920, the union had contracts with 85 percent of men's garment manufacturers in the city and had reduced the workweek to 44 hours.
Under Hillman's leadership, the union tried to moderate the fierce competition between employers in the industry by imposing industry wide working standards, thereby taking wages and hours out of the competitive calculus. The ACWA tried to regulate the industry in other ways, arranging loans and conducting efficiency studies for financially troubled employers. Hillman also favored "constructive cooperation" with employers, relying on arbitration rather than strikes to resolve disputes during the life of a contract. As Hillman explained his philosophy in 1938:
Hillman's belief in stability as the basis for progress was coupled with a willingness to embrace industrial engineering approaches, such as Taylorism, that sought to rationalize the work processes as well. This put Hillman and the ACW leadership at odds with the strong anarcho-syndicalist tendencies within the union's membership, many of whom believed in direct action as a principle as well as tactic. On the other hand, it made Hillman receptive in the early 1920s to the Soviet Union's reconstruction efforts, particularly during its New Economic Policy phase. Hillman led the union into a joint business project with the Soviet Union that brought western technology and principles of industrial management to ten clothing factories in the Soviet Union.
Hillman's support for the Soviet experiment won him the enthusiastic support of the Communist Party USA in the early 1920s; it also further alienated him from those in the Socialist Party and associated with the Daily Forward under the leadership of Abraham Cahan, with whom Hillman and the Amalgamated already had strained relations. While Hillman's relationship with the Communist Party ultimately broke up in the conflict over whether to support Robert La Follette, Sr.'s candidacy for President on the Progressive Party ticket in 1924, Hillman never faced the sort of volcanic upsurge that nearly tore apart the International Ladies' Garment Workers' Union during this period and never undertook the wholesale purges that David Dubinsky and other leaders of the ILGWU used to stay in power. By the end of the decade, after fighting and losing battles in Montreal, Toronto and Rochester, the CP was no longer a significant force in the union.
Internecine warfare between labor sluggers eliminated many of the earliest racketeers. "Little Augie" Jacob Orgen took over the racket, providing muscle for the ILGWU in the 1926 strike. Louis "Lepke" Buchalter had Orgen assassinated in 1927 in order to take over his operations. Buchalter took an interest in the industry, acquiring ownership of a number of trucking firms and control of local unions of truckdrivers in the garment district, while acquiring an ownership interest in some garment firms and local unions.
Buchalter, who had provided services for some locals of the Amalgamated during the 1920s. also acquired influence within the ACWA. One of his allies within the ACWA was Abraham Beckerman, a prominent member of the Socialist Party with close ties to The Forward, whom Hillman used to inflict strongarm tactics on his communist opponents within the union. Beckerman and Philip Orlofsky, another local officer in Cutters Local 4, made sweetheart deals with manufacturers that allowed them to subcontract to cut rate subcontractors out of town, using Buchalter's trucking companies to bring the goods back and forth.
In 1931 Hillman resolved to act against Buchalter, Beckerman and Orlofsky. He began by orchestrating public demands on Jimmy Walker, the corrupt Tammany Hall Mayor of New York, to crack down on racketeering in the garment district, Hillman then proceeded to seize control of Local 4, expelling Beckerman and Orlofsky from the union, then taking action against corrupt union officials in Newark, New Jersey. The union then struck a number of manufacturers to bar the subcontracting of work to non-union or cut rate contractors in Pennsylvania and New Jersey. In the course of that strike the union picketed a number of trucks run by Buchalter's companies to prevent them from bringing finished goods back to New York.
While the campaign cleaned up the ACWA, it did not drive Buchalter out of the industry. The union may, in fact, have made a deal of some sort with Buchalter, although no evidence has ever surfaced, despite intensive efforts of political opponents of the union, such as Thomas Dewey and Westbrook Pegler, to find it. Buchalter claimed, before his execution in 1944, that he had never dealt with either Hillman or Dubinsky, head of the ILGWU.
Hillman was a supporter of the New Deal and Roosevelt from the outset. FDR named him to the Labor Advisory Board of the National Recovery Administration in 1933 and to the National Industrial Recovery Board in 1934. Hillman provided key assistance to Senator Robert F. Wagner in the drafting of the National Labor Relations Act and to Secretary of Labor Frances Perkins in winning enactment of the Fair Labor Standards Act.
Within the AFL, Hillman was one of the strongest advocates for organizing the mass production industries, such as automobile manufacture and steel, where unions had almost no presence, as well as the textile industry, which was only partially organized. He was one of the original founders in 1935 of the Committee for Industrial Organizing, an effort led by John L. Lewis, and became the Vice-President of the CIO when it established itself as a separate union confederation in 1937.
Hillman played a role in nearly every major initiative of the CIO in those years, He oversaw, and provided major financial support for, the Textile Workers Organizing Committee, which sought to establish a new union for textile workers after the disastrous defeat of the United Textile Workers' strike in 1934. The Textile Workers Union of America, with more than 100,000 members, came out of that effort in 1939. Hillman also played a decisive role in mediating the internal disputes that nearly destroyed the United Auto Workers in its infancy in 1938 and helped create the Retail, Wholesale and Department Store Workers Union of America through the CIO's Department Store Workers Organizing Committee.
Hillman and Lewis eventually had a falling out, with Lewis advocating a more independent tack in dealing with the federal government than Hillman. Lewis, however, gradually distanced himself from the CIO, finally resigning as its head and then withdrawing the United Mine Workers from it in 1942. Hillman remained in it, still the second most visible leader after Philip Murray, Lewis' successor.
Hillman was a strong opponent of Nazi Germany and a supporter of U.S. aid to England and France. Roosevelt appointed Hillman to the National Defense Advisory Committee in 1940 and named him associate director of the Office of Production Management in 1941; when FDR created the War Production Board in 1942, he appointed Hillman to serve as the head of its labor division.
As in the case in World War I, Hillman used the influence of the federal government to advance both labor's social goals and its immediate organizing needs. Hillman was not able to persuade the Board to debar labor law violators, but did help introduce arbitration as an alternative to strikes in defense industries. At times, however, Hillman identified so closely with the government that he seemed to have lost sight of his roots in the labor movement; his denunciation of the UAW members who struck North American Aviation in 1941, only to face troops sent by the Roosevelt administration to guard the plant, brought down a great deal of criticism from others within the CIO.
Hillman also believed in the need for unions to mobilize their members politically. He and Lewis founded Labor's Non-Partisan League, which campaigned for Roosevelt in 1936 and again in 1940, even though Lewis himself had endorsed Wendell Willkie that year. Hillman was the first chair of the CIO's Political Action Committee founded in 1942.
Hillman, who had been sick for some time, died in 1946 at his summer home in Point Lookout, Long Island, New York. His successor as head of the ACWA, Jacob Potofsky, took a far less visible role within the CIO, which returned to the AFL in 1955. The Labor Party that Hillman had helped create passed out of existence the same year.
The Amalgamated Housing Cooperative in the Bronx was the first limited equity housing cooperative in the United States. It was funded and inspired by Hillman and Abraham Kazan. A street in the neighborhood, Hillman Avenue, is named for him.
The Sidney Hillman Foundation, established in his honor, gives annual awards to journalists and writers for work that supports social justice and progressive public policy. The first Sidney Hillman Awards were announced in 1950. In addition, from 1949 to 1995 the foundation made annual awards honoring public figures who pursue social justice and public policy for the common good.