This paper addresses the unstable material and social environments that large-scale road construction projects attempt to tame and fix in place as a way of exploring the affective force of roads as technologies for delivering progress and development. Drawing from our ethnography of the construction of two roads in Peru, we trace the disruptive and destabilising processes through which roads come to hold the promise of transformation. We approach roads with curiosity as to their capacity to enchant with respect to three specific promises: speed, political integration and economic connectivity. We suggest that whilst the abstractions of engineering and politics are provisional attempts to demarcate the capacity of roads to bring about the enhancement of international trade, promote the growth of national economies and provide economic opportunity for those prepared to engage with the road's potential, that these practices alone are not sufficient to explain the passionate promise that roads hold in Peruvian society. We suggest, rather, that the promise of stability is invigorated by mundane engagements with unruly forces that threaten to subvert the best laid plans of politicians and engineers. We argue that such forces are integral to the ways in which roads come to endure as enchanted sites of contemporary state-craft despite their capacity to disappoint and/or the likelihood of generating negative consequences. The political and material process of creating roads, calls forth competing, unauthorised and openly unstable dimensions of being - shifting soils and water courses, side-roads and short-cuts which both challenge and reinvigorate the promises of speed, integration and connectivity. © 2012 Copyright Taylor and Francis Group, LLC.