This paper examines the role of work at the cutting of technological change – frontier work – as a driver of prosperity and spatial income inequality. Using new methods and data, we analyze the geography and incomes of frontier workers from 1880 to 2019. Initially, frontier work is concentrated in a set of ‘seedbed’ locations, contributing to rising spatial inequality through powerful localized wage premiums. As technologies mature, the economic distinctiveness of frontier work diminishes, as ultimately happened to cities like Manchester and Detroit. Our work uncovers a plausible general origin story of the unfolding of spatial income inequality.