  Road networks represent a key component of human settlements, such as cities,
towns, and villages, that mediate pollution and congestion, as well as economic
development. However, little is known about the long-term development
trajectories of road networks in rural and urban settings. We leverage novel
spatial data sources to reconstruct and analyze road networks in more than 850
US cities and over 2,500 US counties since 1900. Our analysis reveals
significant variations in the structure of roads both within cities and across
the conterminous US. Despite differences in the evolution of these networks,
there are commonalities and strong geographic patterns. These results persist
across the rural-urban continuum and are therefore not just a product of
accelerated urban growth. These findings refine and extend existing knowledge
and illuminate the need for policies for urban and rural planning including the
critical assessment of new development trends.
