MCJROTC Instructor here
These are some of the issues you are going to deal with trying to get a new program at any High School.
1. Location: Usually needs to be in an area that is supportive of the program. States like Texas, Virginia, NC, SC where there is a large military presence makes it easier to open a school there because there is an infrastructure in place to support a program.
States like Wisconsin, Minnesota, and parts of California that are very liberal have a hard time getting programs because of the anti-military sentiment and they tax military retirement HARD which makes it unattractive to prospective instructors looking towards retirement. States with failing economies (Rust Belt Michigan, Indiana, Ohio) are not on JROTC's radar because of the amount of schools they are closing down and Reduction of Force among faculty in these areas.
2. Student Population: If a school is not rocking close to 3000 students, it is not going to be a candidate for a program. The One-Room Schoolhouse with a Senior Class of 16 is not the answer, to justify funding you have to have numbers (<1000 students, 100 cadets minimum enrolled in JROTC)
3. Sec Army/SecNav/Air Force approval: Each branch has a specific amount of programs they are approved to keep open as mandated by Congress. For any school that has been on a waiting list to receive a JROTC program, you have to shut down a program to get that program open. It's a long process to put a "bullet in that horse" as there are some underperforming programs across that country that remain open.
Your school administration must apply to the specific branch (Student petitions will not cut it gang) and then an area mgr. will come out to your school to do a feasability study (Community, Population Trends, Facilities to maintain a program as far as storage, classroom and office space, areas for drill and marksmanship) Some districts are willing to build the JROTC programs their own Field House, others get shoved in a portable or the basement (Dungeon) out of sight, out of mind.
A lot of variables to consider, and it all comes down to money and infrastructure. Hope this helps.