An example of a relatively early use of the expression in print comes from the entry on Socialism in The American Cyclopedia, edited by George Ripley and Charles Dana and published by D.Appleton and Co. (New York, 1873-76): "[Proudhon proposed] that each citizen should unite in his own person the four necessary factors of production: laborer, capitalist, merchant, and employer" (p. 142). About the same time, The Living Age reprints an article from The Economist, where a close expression "factor in production" is used: "[I]t is natural to ask, has the other factor in production fared equally well -- has the labourer been benefited as much as the capitalist"?" (The Living Age, Volume 120, Issue 1552, March 7, 1874, p. 635). You can get more returns searching the American Memory collection, but there seem to be no hits pre-dating these examples. Yuri Tulupenko