<p>
There are two options:</p>
<ul>
<li><p>The school report that goes along with your application should specify the admission policy and selectiveness of your school. If your school receives 3000 applications for 600 spots, or if it only considers students who were in the top 20% of their elementary/middle school class for admission, that is something that should be pointed out.</p></li>
<li><p>If your school is indeed among the most selective/prestigious schools in the country, and/or if it frequently sends students to the colleges you are applying to, it might already be known to the admissions staff in the US.</p></li>
</ul>