Texas adopts one LIST of books, not just one title. Each district, and sometimes each school or teacher can select the one they want. They can buy ‘off-list’, but not with state money.
Ok, a list. It is still the second largest textbook market in the country, precisely because they select books for the ENTIRE STATE, list or not. This has a significant impact on how textbook publishers write their textbooks for the rest of the country.