Reviewed by: The Road to Inequality. How the Federal Highway Program Polarized America and Undermined Cities by Clayton Nall Craig Pederson The Road to Inequality. How the Federal Highway Program Polarized America and Undermined Cities. Clayton Nall. Cambridge University Press, 2018. xvii and 169 pp., figures, tables, abbrev., bibliog., index. $21.21 paper (ISBN 978-1108405492). Residential preferences have long been studied alongside personal political boundaries of the individual. Research of home purchasing patterns has frequently shown spatial differences between conservative and liberal political ideologies with liberals (Democrats) more likely to live in diversified (racial, cultural, and economic) central cities; whereas conservatives (Republicans) choose to live amongst more homogenous populations throughout the suburbs. Beginning in the 1950s, the push to construct modern highway systems began a process by which individual housing preferences could more easily be acted upon. The ultimate result was mass residential migration creating liberally leaning (and poorer) metropolitan areas and conservative suburban neighborhoods. This resulting response to the introduction of the highway system is the focus of Clayton Nall's book, The Road to Inequality. How the Federal Highway Program Polarized America and Undermined Cities. Studying the impact of the world's largest public works project, the federal highway system, Nall describes in depth how American politics have been impacted and largely framed by the policies shaping the geographic space and boundaries of highway networks. Since inception, highways have been a mechanism of rural, mostly white Republican migration into quickly developing and expanding metropolitan suburbs. The resulting impact of this migration has created a depleted rural population yet cemented a nearly uniform and highly concentrated Republican electorate throughout America's suburbs. Meanwhile, urbanized city-centers are characterized by a diverse blend of races, mostly young, and typically Democrat. The framework of Nall's book traces [End Page 89] the origins of the suburban-urban divide through the alignment of nationally originating policies coalescing with locally adapted, and frequently derived politically partisan transportation policies. Historically, notes Nall, transportation was a non-partisan issue; or at best a bipartisan issue. Prior to the 1960s and 1970s, during a period which Nall refers to as the Transportation Revolution, transportation infrastructure decisions and funding primarily came from the national level. At the time, and to a large degree still today, highway transportation planning and funding was/is equally supported by both Republicans and Democrats. Both sides of the political divide view highway development as an important means of economic growth as it allows for the transmittance of goods throughout the Country. It was not until the Transportation Revolution that Nall notes the growth of partisan politics into transportation decision making as local politics gained a large measure of authority within the decision-making process (primarily through Metropolitan Planning Organizations). The localization of transportation decisions immediately became saturated and tainted by existing hyper-partisan ideologies which fell along the borders of the suburban-urban environment. In his first point of emphasis, Nall contends that once the effects of localized transportation policies set in, the highway system had two primary effects. First, the development of a robust highway system served as a catalyst for migration for which people could now choose their geographic conditions according to preference. Prior to highway development many people, especially the poor, did not have a means of relocating as living close to one's place of employment was a common necessity. Second, highways served as a mechanism of partisan-based geographic sorting. As greater choice of movement was introduced, people sorted themselves according to personal identity and ideology. The resulting self-sorting created the persisting version of the suburban-urban divide where the suburbs are largely white, middle-class, and Republican, while the center-city is younger, multi-racial, educated, and Democratic (party not political structure). Second, Nall conducts an analysis of the political identity change by using US Census data beginning in the 1950s–2000s and compared changes in suburban-urban composition to factors such as density, total length of highway, and proximity of highway exits (also expressed as density). Though spatially diverse, Nall concludes that the highway system helped create suburbs that were significantly less Democratic. This finding was consistent throughout the study area and time...