Francisco Céntola joined the PhD program in 2020. He is interested, broadly, in the human use of energy and materials over long time scales. His dissertation examines the material basis of transportation in California from the late eighteenth to the mid-twentieth century. More generally, this project seeks to explore the main structural features of hunter-gatherer, agrarian, and industrial mobility regimes in western North America and elsewhere. It draws inspiration and pilfers ideas from fields such as ecological economics, urban metabolism studies, and economic geography.