How many miles a week should high school boys be running to be competitive in cross country?

Depends on the competition. 40-50 a week over the summer is a great start (after a gradual build-up to that point).

Are you a parent, a new coach?

Post your question on Health & Fitness. Lots of very experienced runners there (and parents).

There is no magic number of miles. What you should be asking the coach is, "How many miles is appropriate for (me, my kid, etc.) to be running?" There are a lot of factors at play.

Elite 5A schools do about 70 a week.
As El said, good 5A does 40-50 a week (~Elite 4A)
Average 5A is about 35 a week. (~Good 4A, Elite 3A)

Whatever you're doing with them mate don't increase the total anymore than 10% or so per week. To be safe do it every three weeks

Lots of great advice here. Each kid should have a set amount of miles to run over the summer to build their base that is based on their level and goals.

My son runs track and cross country and is about to start his junior year in a 5a school. The coach sits down with each athlete and talks about their summer mileage. He gives them a calendar with certain types/distances of runs to do each day.

I can share more information with you if needed. My son also works with a specialist outside of school that tweaks/gives advice on his mileage, times, core building etc.

My biggest piece of advice is that you should vary places to run in order to not be on pavement so much. Find trails, etc. Don't increase miles too much each week, run with team members, and make sure you watch out for your kid. Some of these coaches in competitive schools will use some pretty aggressive programs that are super heavy mileage and have too many injuries and burn out.

Fartlek set for all times of the season. Run at same pace every surge.. Maybe 5000m pace. 1:1 effort recovery ratio. Ie if you run 90s on jog 90s recovery. Known as Mona Fartlek.

2*90s 4*60s 4*30s 4*15s adds up to 20 minutes total running, depending on your mileage you can do anywhere from 5 minute to 20 minute warm up and cool downs. Used parts of this and progressed to all of it across season with my high school team with positive results.

My two cents: Don't run hard the day before you compete; definitely stretch, maybe a one mile JOG at the most the day before competition just to stay loose, but no hard training or running.

For what this is worth, when I was running marathons consistently, I was training a min 80 miles/week and taking one day off. Don't advise that though unless you have the time and can handle it.