the course of the nineteenth century, manufacturing establishments in the United States used increasing amounts of capital per worker, a process that we refer to as 'capital deepening'. For example, we estimate that, after taking account of changes in the prices of capital goods, capitallabour ratios in manufacturing increased by at least 75 per cent between 1850 and 1880. This capital deepening occurred in tandem with a dramatic shift in the mode and locus of production. Early on, most manufacturing took place in artisan shops. These typically employed the owner-operator and possibly a small number of assistants, producing goods that were designed and made to order. Workers in artisan shops were, on average, highly skilled, but used relatively modest and non-specific capital goods such as a few general-purpose hand tools and a generic workshop that could be employed in many different lines of work.As the manufacturing sector grew over the course of the century, production shifted from artisan shops to factories. There, tasks were subdivided and performed by less skilled workers using more specialized and expensive machinery. This machinery often required more power than human muscle and thus was driven by steam or waterpower. 2 The lumpiness in the capital goods, the regularity and ceaseless energy of inanimate power, and the opportunities afforded by the division of labour meant that production was conducted on a much larger scale than before. From a theoretical standpoint, it is uncertain whether or not these changes increase capital per unit of output. Our estimates, however, indicate that larger establishments used significantly more capital per unit of output than smaller ones.