There is a Chicago event this year which is the mid west. To do an event in Houston there would need to be a good venue. If you have an excellent venue in mind, feel free to post it here.
There is an effort made to make the events accessible to players all over the country. This year there is HB (west), Chicago (mid west), DC (east), and then Vegas as the final.
If anyone has a great venue somewhere, you should let the NPPL know, as they are always looking.