6A district 19 is comprised of 7 Katy high schools. The new Katy high school, Paetow, opens this fall and will be in 5A Div 2 District 10. With all of the building out this way, I doubt it will be too long before Paetow is also in 6A. I also expect another HS to be added relatively soon.
When I moved to Katy in 1989, there were only three 5A schools Katy, Taylor, and Mayde Creek. The growth has been phenomenal.