Theres only one, Clayton Oklahoma. 2.5 hours from Dallas. Do a search on it on here or ridemonkey for picks. Check out the Rogueposse.net. Closest DH course, very rocky need a full travel bike and a truck to shuttle with, from there your only options are in Ark and New Mex.
You wont find directions to the trail as its on private land and to be completely honest you would find the trail head unless you had someone who knew where they are going anyway, but once you know where it is you can ride it anytime. But watch RoguePosse.net on the rides forum and you will see when we are going next and are more than welcome to ride with us, although it wont be for awhile as a whole bunch of us are off to CO tomorrow.
These are old but it gives you an idea http://www.ridemonkey.com/forums/showthread.php?t=111698&highlight=clayton+Oklahoma
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