You could join the US Armed Forces. Per section 328 and 329 of the Immigration and Nationality Act, active duty enlistees may immediately petition for American citizenship, rather than wait the five years normally required. You can be granted citizenship in as little as 3 months, though I'd say 6 months is the true reality. Minimum enlistments are 2 years.
If you're truly 19, as your age thinmabob says, you could probably figure out a way to attend one of the US Service Academies. There are 5 to choose from and they are free, which is pretty damn mustacheian. I can't swear to other schools, but Annapolis gives a great education. This route would take 4.5 years, since you'd have to graduate and get your commission before you could be sworn in as a citizen.
Hope this helped. The military isn't a route for everyone, but it's a fast-track to citizenship that many people don't know about.
Indeed all the academies offer a superb education for free. They are extremely competitive to get into. It would probably be easier to get into Harvard or Stanford. Simply enlisting in the US military is a whole lot easier and does facilitate the path to citizenship.
I hadn't realized that joining the military could open doors to citizenship, but it makes sense -- for the right person.
However, I wouldn't count on a new immigrant gaining admission to one of the service academies. Admission to these academies is incredibly selective (I've known a few students over the years who've been admitted, and they are all above-incredible human beings -- top grades, top physical condition, loads of leadership experience, incredible drive), and I'm pretty sure you need a recommendation from your state senator. I don't know why a senator would recommend a non-American when so many of "his own people" want these limited slots.
Would attending any other american university and going the ROTC route work?
Because getting into those service academies is insanely difficult.
Aye, there's the rub. I was envisioning Mr mohawkbrah using some sort of international exchange, and not state referral. I did enjoy the super human description, though! I'm sure it will make Nords preen his tail feathers.
I realize that the OP has already pointed out that the military is not the preferred option. About the only way for a foreign citizen to join the U.S. military (before having a green card) would be to possess a critical skill in languages or the medical field. During the drawdown, I'd be skeptical that would work.
There's some controversy over how the colleges count their "applicants"-- whether they actually filled out an entire application or just attended a summer sports camp. But by the math used at the service academies (as controversial as that applicant math may be) they're currently harder to get into than Harvard... at least via the Congressional appointment route.
It's still easier to get into a service academy via a Presidential appointment, if you benefit from the parental lottery. These are generally reserved for the children of service-academy alumni who are KIAs, POWs, and retirees. It's also easier to get into the service academies by applying from the enlisted ranks, although if you're turned down for an enlisted appointment then you're still enlisted and have to consider other college options while waiting another year. It's easier to get into USNA via the nuclear-power training pipeline (snarkily called "Academy Prep") although again if you don't make the cut during nuclear power training then you're gonna end up on an aircraft carrier or a submarine. And finally it's "easier" to get into a service academy via the NCAA-- especially a big-bucks sport like football, basketball, baseball, track, swimming, or soccer. But that is still a very difficult road, and it's a real challenge to maintain your overall performance while you're in a varsity sport.
While I appreciate the "superhuman" characterization, it's still possible to get into a service academy with merely good grades and good SATs while having absolutely no idea what you're getting into-- other than admiring how cool your best friend's older brother makes it look. After you show up to take the oath, the only remaining skills you need are persistence and stubborness. The helpful upperclass will tutor you on the rest. Let's not get into how I learned that.
If you already have skills in time management, studying, and self-discipline then I personally feel that you'd get more out of ROTC at a civilian university. But if you're the type of student who'd party your way out of college before Christmas break, then a service academy will definitely provide you with the framework to set you up for success.