Ya it's just high school kids. Texas doesn't have an indoor track season so none of the kids can compete for their school or wearing their school colors...so like Red said they usually compete in their club uniforms or just unattached in practice gear.
A lot of the top Texas high school athletes compete in it so there is some good competition but the meet sure can drag on. In 2010 they had like 40 heats in the guys 200 meters and 30 in the guys 400 meters, girls numbers weren't too far off.