While WiFi was initially designed as a local-area access network, mesh networking technologies have led to increasingly expansive deployments of WiFi networks. In urban environments, the WiFi mesh frequently supplements a number of existing access technologies, including wired broadband networks, 3G cellular, and commercial WiFi hotspots. It is an open question what role citywide WiFi deployments play in the increasingly diverse access network spectrum. We study the usage of the Google WiFi network deployed in Mountain View, CA, and find that usage naturally falls into three classes based almost entirely on client device type, which we divide into traditional laptop users, fixed-location access devices, and PDA-like smartphone devices. Moreover, each of these classes of use has significant geographic locality, following the distribution of residential, commercial, and transportation areas of the city. When comparing the network usage of each device class, we find a diverse set of mobility patterns that map well to the archetypal use cases for traditional access technologies. To help place our results in context, we also provide key performance measurements of the mesh backbone and, where possible, compare them to those of previously studied urban mesh networks.