The railroad brotherhoods, the unions formed in the latter half of the nineteenth century, made minute distinctions between groups that worked alongside each other; as an example, more than twenty years passed between the original chartering of the International Brotherhood of Stationary Firemen and the amendment of its charter to permit the union to represent the oilers and helpers who worked with them.
While both the Knights of Labor and Eugene V. Debs' American Railway Union attempted to organize railroad workers on an industrial basis, those efforts were defeated, in some cases by government intervention, injunctions, and force of arms.
In the ILGWU, for example, the cutters, who were often primarily of English, Irish, and German stock, were almost exclusively males, were better paid, and were typically more skilled, often looked down on the immigrant, largely female, unskilled "operators" who ran sewing machines in their shops or elsewhere.
As long as the craft unions were the dominant power in the AFL, they took every step possible to block the organizing of mass production industries.
The IWW was seriously damaged by government prosecution and vigilantism in the post-war red scare that reached its peak in 1919, and in the Palmer Raids of the same period.
This dispute came to a head at the AFL’s convention in Atlantic City in 1935, when William Hutcheson, the President of the Carpenters, made a slighting comment about a member of the fledgling union of tire factory workers who was delivering an organizing report.
After some more words Lewis punched Hutcheson, knocking him to the ground, then relit his cigar and returned to the rostrum.
Even the Carpenters took in sawmill workers who had organized on an industrial basis, although the union continued to treat them as second-class members until they seceded to form the International Woodworkers of America in 1937.