Locations of animate and inanimate items are tracked over time. Tracking policies concerning the items are enforced, based on detected spatiotemporal events. Multiple routers each maintain a captive network to which mobile computing devices automatically connect. Users register mobile computing devices, which are associated with items to be tracked. A backend server maintains records concerning registered mobile computing devices. Records contain identifiers of registered mobile computing devices and their associated items, as well as categorization information and tracking policies concerning the items. Over time, registered mobile computing devices are moved around, causing them to connect to and disconnect from different captive networks. These connection events are reported to the backend, which uses this data to track locations of items over time. Based on this tracking, the backend determines when specific tracking policies of specific items dictate that alerts are to be sent, and transmits alerts to target users accordingly.