There are some youth XC programs that are feeder programs now to middle schools in CO Springs and Front Range area. Kokopelli (Sam Chalenga's kids are in this), Boulder Mountain Warriors (both Ritz's and Goucher's kids are/have run for them). These kids come into Middle School ready to go and are usually are good right off the bat in 9th grade as well. Mentally and physically prepared to run fast times.
The XC/Track scene for youth (Elementary school age) is also hot in CO right now. The kid who won USATF 800m and 1500m in Eugene (age 10) has been running in a bunch of these youth meets. The other kid who's been crushing the age 11 group, and ran in Eugene, also runs a bunch of the youth meets (you can track his history back to age 8 on milesplit).
Wyoming has been getting in on this as well. There's a new youth (K-5) XC program that ran in some of the Boulder meets last year and the year previous. They had a girl who almost won the whole race last year at the Boulder (teamboco?) fall youth XC race against the powerhouses like Kokopelli and Boulder Mountain Warriors.
Point is that talent is being spotted very early, nurtured, and graduated to the highschool ranks. This didn't always happen. When other kids watch these talents rise in middle school tehy want to get in on the action and they join XC early. It's a snowball effect.