Concerning laws on boot camps, Federal law does contain references to the use of boot camps and the like, apparently approving of the phenomenon. A boot camp for kids or some other confrontational rehabilitative program is governed by the Shock Incarceration Program in the U.S. legal code. This section states that, for a period of incarceration of over one year but not exceeding 30 months, an adult or child tried as an adult may undergo boot camp training for a maximum period of six months. There are, indeed, Federal boot camps overseen by the Bureau of Prisons, but they are few in number.
As for State governments, they also may offer a boot camp for kids and adults, and sometimes, not as an extension of the prison system, but at least nominally as an extension of their probation. In all, though, statistics on Federal- and State-run boot camp programs are fairly hard to find.
Often what is known is gleaned through surveys, and even then, only a handful of states targeted by these measures are liable to report. Besides this, data is usually available for official State-operated boot camps affiliated with prison systems. Independent estimates would place the number of individuals in public boot camps over 7,000 people total.