Check out national professional organizations.
The National Society of Black Engineers (NSBE) has created an amazing pre-college initiative to engage African-American youths in STEM. NSBE SEEK (Summer Engineering Experience for Kids) is a three-week program for students in grades 3-8. The free camp, led by college science and engineering students, engages hundreds of students in fun learning activities in cities across the nation. Additionally, prospective students can engage in collegiate programs during the summer, exposing them to math and science courses at a university level.