Check for signs, Texas allows carry in state parks but the buildings are like any other building/place of business. If they have a sign banning guns (that's a legal sign in your state) then no go!!
Well as I read FAQ about Texas Concealed Handgun License it says; "...carry is still banned in park visitor centers, ranger stations and administrative buildings and offices staffed by federal employees...". I would not carry in any building that is 'manned' just to be safe.
Guess I'd go to your state attorney general's web site and see if the laws are posted online or give them a call and see if they can point you in the right direction.
Last thing I'd be doing is taking somebody's word for it on a public forum.