The Gas Index report and results were released on December 15, 2020, at the website https://thegasindex.org
The complete model code for replicating the results is included in this repository.
The reposistory also includes all of the model's input files, except for U.S. Census TIGER-Line files for census tract boundaries, since those files are large (> 600 MB). You can download the census tract data by state from the U.S. Census website.