Expanding e-commerce and delivery benefit consumers with increased flexibility and convenience. However, there is a potential impact on vehicle miles traveled (VMT) by delivery and personal vehicles, and the resulting energy consumption, air quality, and congestion. Delivery trips could replace personal vehicle trips, but if not could add to (or supplement) shopping-related VMT for a given household. We examine the benefits of e-commerce to consumers and the impact on personal shopping trips, and how these differ across item types and household child status and income. We find that high-income households and households with children care relatively more about time saving from deliveries. We find that on average, deliveries substitute for 12% of vehicle shopping trips, but for 9% of purchases deliveries supplement personal shopping trips. Underlying these averages are two main types of households: those for whom all deliveries substitute for trips (between 55% and 70% of households) and those for whom all deliveries supplement trips (between 20% and 35% of households). There is significant heterogeneity across households with and without children and with high or low income with respect to the use of delivery. While time savings was more likely to motivate higher-income households and households with children to use delivery, this did not translate through to these households substituting for more of their trips; deliveries of prepared meals for both these categories of households are relatively more likely (15% for households with children, and 12% for higher-income households) to supplement, and not substitute for, personal trips.