A computer implemented method to determine locations of user computing devices, comprising: determining, by one or more computing devices and at a first time, that a user computing device is located outside a geofence boundary encompassing a particular point of interest, wherein the user computing device is separate and distinct from the one or more computing devices; determining, by one or more computing devices and at a second time that is subsequent to the first time, that the user computing device is located inside the geofence boundary encompassing the particular point of interest; and, in response to determining at the second time that the user computing device is located inside the geofence boundary encompassing the particular point of interest: communicating, by the one or more computing devices, instructions to the user computing device to invoke a wireless signal detection module associated with the user computing device; receiving, by the one or more computing devices and from the user computing device, wireless signal data for a particular wireless signal that is available to the user computing device after receipt of the particular wireless signal by the wireless signal detection module, the wireless signal data comprising an identifier that is unique to the particular wireless signal; determining, by the one or more computing devices and based on the wireless signal data comprising the identifier, that the particular wireless signal available to the user computing device is associated with the particular point of interest; determining, by the one or more computing devices and in response to determining that the particular wireless signal is associated with the particular point of interest, that the user computing device is at the particular point of interest; and communicating, by the one or more computing devices and in response to determining that the user computing device is at the particular point of interest, a signal to the user computing device to cease determining the particular wireless signal that is available to the user computing device. determining, by one or more computing devices and at a first time, that a user computing device is located outside a geofence boundary encompassing a particular point of interest, wherein the user computing device is separate and distinct from the one or more computing devices; determining, by one or more computing devices and at a second time that is subsequent to the first time, that the user computing device is located inside the geofence boundary encompassing the particular point of interest; and, in response to determining at the second time that the user computing device is located inside the geofence boundary encompassing the particular point of interest: communicating, by the one or more computing devices, instructions to the user computing device to invoke a wireless signal detection module associated with the user computing device; receiving, by the one or more computing devices and from the user computing device, wireless signal data for a particular wireless signal that is available to the user computing device after receipt of the particular wireless signal by the wireless signal detection module, the wireless signal data comprising an identifier that is unique to the particular wireless signal; determining, by the one or more computing devices and based on the wireless signal data comprising the identifier, that the particular wireless signal available to the user computing device is associated with the particular point of interest; determining, by the one or more computing devices and in response to determining that the particular wireless signal is associated with the particular point of interest, that the user computing device is at the particular point of interest; and communicating, by the one or more computing devices and in response to determining that the user computing device is at the particular point of interest, a signal to the user computing device to cease determining the particular wireless signal that is available to the user computing device. communicating, by the one or more computing devices, instructions to the user computing device to invoke a wireless signal detection module associated with the user computing device; receiving, by the one or more computing devices and from the user computing device, wireless signal data for a particular wireless signal that is available to the user computing device after receipt of the particular wireless signal by the wireless signal detection module, the wireless signal data comprising an identifier that is unique to the particular wireless signal; determining, by the one or more computing devices and based on the wireless signal data comprising the identifier, that the particular wireless signal available to the user computing device is associated with the particular point of interest; determining, by the one or more computing devices and in response to determining that the particular wireless signal is associated with the particular point of interest, that the user computing device is at the particular point of interest; and communicating, by the one or more computing devices and in response to determining that the user computing device is at the particular point of interest, a signal to the user computing device to cease determining the particular wireless signal that is available to the user computing device.