Marcellus in NY had a stretch from around 2009-2013 where they had a 47/1:50 guy, a 4:06 miler, a 1:51/4:13 guy, and a 1:53/4:13 guy. The latter two both ran sub-4:00 in college and one of them, Jesse Garn, went on to become a fairly successful pro runner with a PB of 1:45.0 for 800. Enrollment around 500.
Also from New York, the Argyle girls of 2003 were likely one of the greatest high school XC teams of all time (no NXN back then) and Argyle dropped the program. Three or four of their runners transferred to nearby Saratoga and went on to win the inaugural Nike Team Nationals with a score of 51 points, still one of the lowest in the history of the meet. Enrollment around 200 for Argyle.