Hi there, and congrats for trying to get some extra CDL endorsements under your belt! They're not easy to get, but if you're planning to make a career out of trucking, those endorsements are worth their time
Since you're asking specifically about Texas, here are all the CDL endorsements in the state that I'm aware of:
1) H (Hazardous Materials) - if you want to carry hazardous materials (might require a background check from the TSA)
2) N (Tank Vehicle) - for driving vehicles that carry liquids or gaseous materials in tanks
3) P (Passenger) - this lets you drive vehicles that can carry 16 or more passengers
4) S (School Bus) - this lets you operate and drive school buses
5) T (Double/Triple Trailers) - you can get this if you want to pull double or triple trailers
6) X (Combination of Tank Vehicle and Hazardous Materials) - basically combines the N and H endorsements
I hope that helps, and best of luck!
