The nature and power of organized labor in the United States is the outcome of historical tensions among counter-acting forces involving workplace rights, wages, working hours, political expression, labor laws, and other working conditions. Organized unions and their umbrella labor federations such as the AFL–CIO and citywide federations have competed, evolved, merged, and split against a backdrop of changing values and priorities, and periodic federal government intervention.

In most industrial nations, the labor movement sponsored its own political parties, with the US as a conspicuous exception. Both major American parties vied for union votes, with the Democratic Party usually much more successful. Labor unions became a central element of the New Deal coalition that dominated national politics from the 1930s into the mid-1960s during the Fifth Party System.Steve Fraser and Gary Gerstle, eds. The Rise and Fall of the New Deal Order, 1930-1980 (1990) Liberal Republicans who supported unions in the Northeast lost power after 1964.Nicol C. Rae, The Decline and Fall of the Liberal Republicans: From 1952 to the Present (1989) In recent decades, an enduring alliance was formed between labor unions and the Democrats, whereas the Republican Party has become hostile to unions and collective bargaining rights.

The history of organized labor has been a specialty of scholars since the 1890s, and has produced a large amount of scholarly literature focused on the structure of organized unions. In the 1960s, the sub-field of new labor history that emerged as social history was gaining popularity broadly, with a new emphasis on the history of workers, including unorganized workers, and their gender and race. Much scholarship has attempted to bring the social history perspectives into the study of organized labor.David Brody, "Reconciling the Old Labor History and the New," Pacific Historical Review 72 (February 1993), 111-126.

By most measures, the strength of organized labor has declined in the United States over recent decades.

Organized labor prior to 1900 The history of labor disputes in America substantially precedes the Revolutionary period. Around 1619, when the first elections in the Virginia colony were held, the Polish craftsmen decided to refuse to work, on the basis that they were not allowed to vote. In 1636, for instance, there was a fishermen's strike on an island off the coast of Maine and in 1677 twelve carmen were fined for going on strike in New York City.Commons, ii-iii However, most instances of labor unrest during the colonial period were temporary and isolated, and rarely resulted in the formation of permanent groups of laborers for negotiation purposes. Little legal recourse was available to those injured by the unrest, because strikes were not typically considered illegal. The only known case of criminal prosecution of workers in the colonial era occurred as a result of a carpenters' strike in Savannah in 1746.

Legality and Hunt (1842)

By the early 19th century, the career path for most artisans still involved apprenticeship under a master, followed by moving into independent production.Tomlins, 111 However, over the course of the Industrial Revolution, this model rapidly changed, particularly in the major metropolitan areas. For instance, in Boston in 1790, the vast majority of the 1,300 artisans in the city described themselves as "master workman". By 1815, journeymen workers without independent means of production had displaced these "masters" as the majority. By that time journeymen also outnumbered masters in New York City and Philadelphia.Tomlins, 112 This shift occurred as a result of large-scale transatlantic and rural-urban migration. Migration into the coastal cities created a larger population of potential laborers, which in turn allowed controllers of capital to invest in labor-intensive enterprises on a larger scale. Craft workers found that these changes launched them into competition with each other to a degree that they had not experienced previously, which limited their opportunities and created substantial risks of downward mobility that had not existed prior to that time.

These conditions led to the first labor combination cases in America. Over the first half of the 19th century, there are twenty-three known cases of indictment and prosecution for criminal conspiracy, taking place in six states: Pennsylvania, Maryland, New York, Louisiana, Massachusetts, and Virginia.Tomlins, 128 The central question in these cases was invariably whether workmen in combination would be permitted to use their collective bargaining power to obtain benefits—increased wages, decreased hours, or improved conditions—which were beyond their ability to obtain as individuals. The cases overwhelmingly resulted in convictions. However, in most instances the plaintiffs' desire was to establish favorable precedent, not to impose harsh penalties, and the fines were typically modest.Commons, viii

One of the central themes of the cases prior to the landmark decision in Commonwealth v. Hunt, 45 Mass.111 (1842), which settled the legality of unions, was the applicability of the English common law in post-revolutionary America. Whether the English common law applied—and in particular whether the common law notion that a conspiracy to raise wages was illegal applied—was frequently the subject of debate between the defense and the prosecution.Tomlins, 133 For instance, in Commonwealth v. Pullis, 3 Doc.Hist.59 (1806), a case against a combination of journeymen cordwainers in Philadelphia for conspiracy to raise their wages, the defense attorneys referred to the common law as arbitrary and unknowable and instead praised the legislature as the embodiment of the democratic promise of the revolution.Lloyd, 107-24 In ruling that a combination to raise wages was per se illegal, recorder Moses Levy strongly disagreed, writing that "[t]he acts of the legislature form but a small part of that code from which the citizen is to learn his duties... [i]t is in the volumes of the common law we are to seek for information in the far greater number, as well as the most important causes that come before our tribunals."

As a result of the spate of convictions against combinations of laborers, the typical narrative of early American labor law states that, prior to Hunt in Massachusetts in 1842, peaceable combinations of workingmen to raise wages, shorten hours or ensure employment, were illegal in the United States, as they had been under English common law. In England, criminal conspiracy laws were first held to include combinations in restraint of trade in the Court of Star Chamber early in the 17th century.Commons, iv The precedent was solidified in 1721 by R v Journeymen Tailors of Cambridge, which found tailors guilty of a conspiracy to raise wages.(1721) 8 Mod 10, 88 ER 9; Commons, iv Leonard Levy went so far as to refer to Hunt as the "Magna Carta of American trade-unionism",Levy, 183 illustrating its perceived standing as the major point of divergence in the American and English legal treatment of unions which, "removed the stigma of criminality from labor organizations".

However, case law in America prior to Hunt was mixed. Pullis was actually unusual in strictly following the English common law and holding that a combination to raise wages was by itself illegal. More often combination cases prior to Hunt did not hold that unions were illegal per se, but rather found some other justification for a conviction.Witte, 825 After Pullis in 1806, eighteen other prosecutions of laborers for conspiracies followed within the next three decades. However, only one such case, People v. Fisher, also held that a combination for the purpose of raising wages was illegal. Several other cases held that the methods used by the unions, rather than the unions themselves, were illegal. For instance, in People v. Melvin, cordwainers were again convicted of a conspiracy to raise wages. Unlike in Pullis, however, the court held that the combination's existence itself was not unlawful, but nevertheless reached a conviction because the cordwainers had refused to work for any master who paid lower wages, or with any laborer who accepted lower wages than what the combination had stipulated. The court held that methods used to obtain higher wages would be unlawful if they were judged to be deleterious to the general welfare of the community.Tomlins, 139–147 Commonwealth v. Morrow continued to refine this standard, stating that, "an agreement of two or more to the prejudice of the rights of others or of society" would be illegal.Shaler, 24

Another line of cases, led by Justice John Gibson of the Supreme Court of Pennsylvania's decision in Commonwealth v. Carlisle, held that motive of the combination, rather than simply its existence, was the key to illegality. Gibson wrote, "Where the act is lawful for an individual, it can be the subject of a conspiracy, when done in concert, only where there is a direct intention that injury shall result from it". Still other courts rejected Pullis rule of per se illegality in favor of a rule that asked whether the combination was a but-for cause of injury. Thus, as economist Edwin Witte stated, "The doctrine that a combination to raise wages is illegal was allowed to die by common consent. No leading case was required for its overthrow".Witte, 827 Nevertheless, while Hunt was not the first case to hold that labor combinations were legal, it was the first to do so explicitly and in clear terms.

Early federations

The Brotherhood of Locomotive Engineers and Trainmen — now part of the International Brotherhood of Teamsters — was founded in May 1863.

The National Labor Union (NLU), founded in 1866, was the first national labor federation in the United States. It was dissolved in 1877.

The regional Order of the Knights of St. Crispin was founded in the northeast in 1867 and claimed 50,000 members by 1870, by far the largest union in the country. A closely associated union of women, the Daughters of St. Crispin, formed in 1870. In 1879 the Knights formally admitted women, who by 1886 constituted 10 percent of the union's membership,Kessler-Harris, Out to Work, pp. 85–6 but it was poorly organized and soon declined. They fought encroachments of machinery and unskilled labor on autonomy of skilled shoe workers. One provision in the Crispin constitution explicitly sought to limit the entry of "green hands" into the trade, but this failed because the new machines could be operated by semi-skilled workers and produce more shoes than hand sewing.John P. Hall, "The Knights of St. Crispin in Massachusetts, 1869-1878", The Journal of Economic History 18 (June 1958), 161-175.

Railroad brotherhoods

With the rapid growth and consolidation of large railroad systems after 1870, union organizations sprang up, covering the entire nation. By 1901, 17 major railway brotherhoods were in operation; they generally worked amicably with management, which recognized their usefulness.Walter Licht, Working for the Railroad: The Organization of Work in the Nineteenth Century (1983) pp. 264–68 Key unions included the Brotherhood of Locomotive Engineers (BLE), Brotherhood of Maintenance of Way Division (BMWED), the Order of Railway Conductors, the Brotherhood of Locomotive Firemen, and the Brotherhood of Railroad Trainmen.In 1969, all except the BLE joined with the Switchmen's Union to become the United Transportation Union (UTU). In 2004 the BLE joined the Teamsters. Their main goal was building insurance and medical packages for their members, as well as negotiating work rules, such as those involving seniority and grievance procedures.