We live in consumer cities, where the scale of the city provides shoppers with a diversity of retail and service experiences (Glaeser et al., 2001). For a given person, the accessibility of these experiences depends on three features: which neighborhood they live in, its transportation links to other neighborhoods, and the scale of services in those neighborhoods. We call a neighborhood with high accessibility vibrant. In many rich cities – including every U.S. city but one – most people own cars, and drive to these services. Driving requires parking, and therein lies the rub: parking is necessary for driving, but it uses land that could have gone to creating more services or homes. Walking and transit have no such prerequisites, and a city that relies on them will be able to make full use of its land for productive purposes. However, they hinder mobility in other ways: walking does not get you far, and using transit requires adhering to the routes and stops the city’s transit agency provides. In this paper, we develop a model of a spatial consumer city to highlight the tradeoff between people or parking. We use shopping mode share data to calibrate quantitative versions of the model for a transit city and a driving city. We show that investments in light rail in the driving city have little effect on mode share. The addition of shared scooters act as a complement to light rail in resolving the last mile challenge, but the effect remains quite small. Parking lowers the vibrancy of places regardless of the mode used to get there, and households respond to the option of parking by choosing to drive for most trips.
