Land was an unambiguous constraint for growth in the pre-industrial period. In Britain it was overcome partly through the transition from traditional land-based goods to coal (vertical expansion) and partly through accessing overseas land, primarily from colonies (horizontal expansion). Kenneth Pomeranz suggested that horizontal expansion may have outweighed vertical expansion in the first decades of the nineteenth century. Taking a more complete approach to trade, we find that Britain was a net exporter of land embodied in traded commodities, apart from in the early nineteenth century, when potash (rather than cotton or timber) constituted the major land-demanding import from North America. The vertical expansion was generally larger than the horizontal expansion. In other words, Britain was not simply appropriating flows of land and resources from abroad but simultaneously providing its trading partners with even more land-expanding resources.
