You are such a dope.

Here is the age eligibility for NY.
AGE AND GRADE: Regulation of the Commissioner of Education: A student shall be eligible for interschool competition in grades 9, 10, 11 and 12 until his/her nineteenth birthday. If the age of nineteen years is reached on or after July 1, the student may continue to participate during that school year in all sports.

Here it is for schools like Landon and Bullis: Any student turning nineteen years of age prior to September 1 is not eligible for that school year.

Here it is for MD schools: Students who are 19 years old or older as of August 31 are ineligible to participate in interscholastic athletics.

They are all the same. Go hit the wall, kid.