Seeing Availability is a collection of research and maps that were published by New City Design Chicago as part of The Geography of Emptiness: Newcity Explores the 2021 Chicago Architecture Biennial (CAB 2021). The full article can be found at the link below.
https://design.newcity.com/2021/09/16/what-is-available-seeing-125-million-square-feet-of-chicago/