I live in SV and my son competes in math and robotics competitions. I have never seen an African American at a competition. Robotics has more caucasians. Still below 50% but Bay Area skews Asian so hard to tell.

Elementary School Math competitions are almost completely SE Asian and South Asian. Maybe 2% Caucasian. Girls/boys are about 50/50 across Asians. Fewer Caucasian girls than boys but small sample size.

Just random observations.