Well said.
I believe Dartmouth XC wants 4:20 or faster for the mile and 9:20 or faster for 3200m by end of Junior year of high school. So you're close (and maybe more recruitable as a mid-distance rather than a long distance runner, as 1:55 is pretty darn fast, dude!).
Recent Dartmouth long-distance runner I know ran 4:16 (1600m) and 9:18 (3200m) in high school I think, scored 32 ACT and applied EARLY. Plus you'll need great grades, high APs (4s and 5s), leadership, community involvement, stellar catchy essays, impressive achievement tests, and summers well spent -- you know, the usual.
(General note on essays: don't rewrite your resume in prose. Also, avoid the "I faced a hurdle but managed to overcome it!" essay, the "community-service-volunteer experience that changed my perspective and my life!" essay, and the dying-parent essay. Sounds harsh I know, but admissions officers have told me they get so many of these types they literally pile them into stacks. Rather, albeit stylishly, reveal something honest, personal, even small yet with some genuine emotion about yourself. )
(General note on academic areas of interest: the most common prospective majors are Economics, Gov'y, Engineering, Bio-Chemistry and English.... because top colleges send so many of their grads off to business school, med school, law school and careers in engineering. To make yourself stand out a bit, if asked, consider relating a less crowded field of study as your intended major. Those smaller departments [Portuguese, Anthropology, Creative Writing, Religion, Medieval German poetry, etc.] need majors too, and the dean of admissions knows he or she should check those boxes during the process in order to keep those department heads happy/off his or her back. That said, you do need to show some prior interest to prove authenticity ....)
Some schools prefer the applicant with startlingly distinct skills: eg the refugee from a family of Algerian high-wire jugglers who translated Kipling's JUST SO stories into Arabic last summer.... That's awesome, but it seems Dartmouth welcomes generally well-rounded students with equal, if not greater, fervor/frequency.
Early decision at Dartmouth is actually statistically easier than regular admission, because school spirit -- which includes a student body that really really wants to be up in Hanover -- is particularly important to Dartmouth and thus to its admissions department. (That's not the case for all places; applying early to UPenn is statistically harder than regular admission and thus can actually hurt you, as I recall).
Also, definitely reach out to the coaching staff. Let them hear your passion for running and for Dartmouth. Keep them apprised of noteworthy races, times and PRs this fall with friendly emails. Get your coach(es) to call and talk you up. The value of building a personal connection deserves underlining here.
Btw, never refer to Dartmouth as a university. Though it does have a top-10 b-school plus world-renowned engineering and medical grad schools, it takes great pride in the quality of its UNDERGRADUATE education -- ranked as one of if not the best in the country -- because students are taught by the professors, not TAs in a masters or PhD program. "Dartmouth College", never "Dartmouth University".
Good luck! And remember that for all our "good" advise and for all your best efforts, it is really a crap-shoot. The average admissions officer at an average high-end college spends an average of just 8-12 minutes (!!!) on any single application (a lot less time than I've spent writing this reply!). The Ivys, Stanford, BC, Georgetown, Duke, Williams, Berkeley et al. -- they all have far more qualified applicants than they can possibly accept ... so they end up rejecting tons of perfectly great candidates, unfortunately. So if you don't get in to The Big Green early, make sure you apply to PLENTY of other schools... and keep your fingers crossed!