Shopping trips and deliveries then and now: How the behavioral shift differs by income level and urban size

Online shopping has significantly increased for the past decade. As e-commerce grows and evolves since its first appearance, consumers’ shopping behaviors also change, leading to the co-evolution of people’s shopping trips and urban freight deliveries. This co-evolution has important impacts on traffic, vehicle-miles-traveled (VMT) and parking demand in the short term, and is expected to influence residential choice and land-use patterns in the long term. However, the existing studies have not examined how the relationship among shopping channels changed over time. To address this knowledge gap, this research investigated how the complex relationship between delivery and in-store shopping trips changed from when e-commerce was relatively small to a stabilized stage, i.e., from 2009 to 2017, using the National Household Travel Survey (NHTS) data. The results from path analyses showed that the relationships among delivery, non-motorized shopping trip, and motorized shopping trip significantly shifted during an eight-year period. Not only the relationship among shopping channels but also the impacts of socio-demographic factors on shopping had changed over time. Furthermore, the behavioral shift varied by income level and urban size. This research is the first attempt investigating a heterogeneous historical trend from the transportation perspective. An understanding of how the relationship has been shifted and affected by income and urban environments will provide valuable insights into proactively planning and establishing freight demand management as well as addressing the inequality issue. The lessons learned will also be of assistance to better understand how consumers will respond to the emerging freight delivery service forms (e.g., prepared meals and grocery delivery) and their impacts on both passenger and freight transportation systems.