In Washington you need an additional motorcycle endorsement on your license.
It is an additional $54 and last for 6 years at which time you can renew it.
There are no age restrictions.
I was grandfathered in because I've been riding since motorcycles were powered by coal
but here you now need to take a riding class which last about 6 weeks or so and then pass the test,
both written and riding.
I have no idea what the requirements in Texas are.
Probably something like handing you a new set of spurs and yelling "Yeeeehaw!!!!"