Looking at the map, you'll see that Texas also has about half of the USA's complete border with Mexico. Import/Export is a large part of the Texas economy.

Also, Texas is geographically at about the same latitude as Florida, which means longer growing seasons.

As far as the military goes, Texas, like other states, has the National Guard and Reserves. However Texas also has the Texas State Guard, which is a military organization that only answers to the Governor of Texas.

And, Texas is required to maintain a balanced budget. Although federal programs are a source of revenue that the state would have to forego.