 Can not find data about the geographic boundary information 

Hello! 
According to your paper, the geographic boundary information is needed in this project (it seems to be stored in ../data/ChiCA_gps/ChiCaGPS.shp). I searched the US census survey, find it hard to get the geographic information of Chicago and worry that it is different from your format.
Could you please give the exact URL of this data or upload it?