During a natural disaster like Hurricane Florence, crisis maps can be an invaluable source of information about road and bridge closures and other infrastructure outages. Trouble is, that information doesn’t always trickle down to mobile phones, which is where most people get their maps. (Especially when authorities have trouble keeping up with road closures on their own maps.) CityLab’s Clare Tran explores this question, looking at, for example, how Waze incorporates road closure data from Esri and its volunteers.