In this paper, we analyse economic discourse in debates over the production boundary, asking how the boundaries around economic categories change over time. Using a sample of economic textbooks from the late nineteenth to mid-twentieth century we analyse the evolution of the category of productive labour, finding that in the mid-twentieth century economists came to cohere around a conceptualization of productive activity that framed productive labour as any utility that was paid for on a market. Central to this outcome was the development of national accounting statistics that economists came to adopt in their analytical toolkit, which rendered invisible unpaid labour activities. Through this case we can see that statistical representations of the economy can redefine theoretical concepts and redraw the boundaries around economic categories, in this case transforming the boundary of productive labour into that of paid labour.