Where is the largest ROTC program in the United States located?
5th Reserve Officers' Training Corps Brigade: The 5th Reserve Officers' Training Corps Brigade is an Army Reserve Officers' Training Corps brigade based at Fort Sam Houston, Texas. Army Reserve Officers' Training Corps:  It is the largest ROTC program, with 20,000 ROTC cadets in 273 ROTC programs at major universities throughout the United States.
Fort Sam Houston, Texas