Grimes A, Berkley-Patton J, Allsworth JE, Lightner JS, Feldman K, Never B, Drees BM, Saelens BE, Powell-Wiley TM, Fitzpatrick L, Bowe Thompson C, Pilla M, Ross K, Steel C, Cramer E, Rogers E, Baker C, Carlson JA. Impacts of zero-fare transit policy on health and social determinants: protocol for a natural experiment study. Front Public Health. 2024; 12:1458137.