I can't think of such a sign within a 100 miles of here (Dallas). And posted a question to that effect in the Texas forum, no one else seems to know of one, either.
It's not just the grade that's the issue. For a 7% or so grade to be marked, it's got to be a long grade, and that's what we're missing around here.
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"be careful this rando stuff is addictive and dan's the 'pusher'."