“The most disastrous obstacle to labor unity in the 1850s was the reaction of native workers to the arrival of several million impoverished Irish and German laborers who came in a flood after European crop failures of the 1840s. These new immigrants provided cheap labour power for the growth of New England factories as well as armies of raw muscle for railroad expansion and coalfields. They were met by the universal hostility of a native working class which rioted against them, evicted them from workplaces, refused them admission into trade unions, and tried to exclude them from the franchise. Partly rooted in economic rivalries in the labour market, the Yankee-versus-immigrant polarization in the working class also reflected a profound cultural antagonism that would hinder the efforts at labor unity for more than a century.”