^^ what he said. Houston chapter assignment numbers are roughly in line with their percentage of overall TASO membership; like Elvis said, coaches aren't picking Houston because it's Houston, but more likely, that Houston is the closest chapter, or that's who calls their home games anyways, particularly with 5A and up.
Eventually I'd like to heat map the games by chapter, to see how far chapters are going outside their local area. Right now, my instinct (from looking at this spreadsheet constantly) says Houston isn't getting much outside their local area matchups, unlike a couple other chapters.