Mr. Block, an IWW anti-racist cartoon from the early 1900s

Here's a summary from a 1998 conference on American labour history. It shows how race-baiting was a capitalist tool, and that white workers did not benefit materially from that division. (Or, to put it another way, the 'psychological wage' white workers get from racism was abandoned for a higher, money-wage.) This is where socialists can have an impact on activism. And it's a great story:

"In “Having Their Way: Alabama Operators Play the Race Card, 1908–21,” Brian Kelly (Florida International University) explored an issue raised by W.E.B. Du Bois at the time—that employers deliberately fostered racial antagonism as a union-obstructing tactic. While Kelly acknowledged that this notion is currently out of favor (“regarded as reductionist”), he also suggested that fashionable emphases on the centrality of race and the agency of the oppressed tended to elide situated power relations and their implications. Recent work, for example, arguing that Jim Crow chiefly safeguarded the interests of white workers (hence privileging race over class) obscures the advantages employers held and the gains they reaped from racial divisiveness (and conversely the significance of cross-race unity among workers).


"This point can be documented in Alabama’s coal mining history; between 1900 and the 1920s, Jim Crow became the mainstay in mine operators’ campaigns to break the influence of the United Mine Workers (UMW) and/or to prevent further organization. Indeed, the district’s early twentieth-century mine owners were “obsessed with race,” creating a system of “racial paternalism” as a counterweight to unionization, backed by substantial police–military forces. The Alabama Coal Operators Association (ACOA), following a bitter 1908 strike, strove to implement a welfare capitalism adapted to the southern racial setting.

"Moreover, as a part of a broad-gauged drive to increase productivity, ACOA members actively recruited African-American miners, whose work force share rose from fifty percent c. 1908 to seventy-five percent by 1920. The UMW mounted a wartime organizing effort in 1917, making special appeals to black miners’ grievances, which included operators’ coercive efforts to prevent them from leaving the camps for better opportunities elsewhere, including up north. As African Americans joined the union in droves, owners claimed German plots were afoot and hired “patriotic” black spokesmen to warn against “the white man’s union.” Workers, black and white, largely ignored such propaganda.


"In mining, Kelly argued, white workers did not derive benefits from the greater oppression blacks suffered. Rather, white and black miners built their unions in tandem, then struck together in 1920, threatening the foundations of white supremacy and provoking a massive employers’ response (race baiting in the local press, physical force from Ku Klux Klan groups and the state militia, and lynch mob violence). The biracial UMW strikers held their lines through a six-month walkout, and even in defeat left behind what Kelly termed “a stirring example of interracial solidarity” in the face of capitalist power."