Not only should they be there in numbers, but the fall is the best time of year for Copperheads in East Texas. I haven't ever hunted northeast TX much, but further south around the pineywoods of SE and EC Texas, they are downright abundant on roads at night in the fall. The trick is to find something other than copperheads!
As it gets cooler in the fall, I used to find lots of copperheads under pine bark slabs around rotting pine stumps (not on the stump, but under the slabs around the base). It was a very predicatible way to find them in early November days when other snakes were fewer and far between.
You can also find coralsnakes on quiet sandy roads in September and particularly October in east TX. They are often found on the roads during daylight hours, but they haul butt off the road when you approach.
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Chris Harrison
San Antonio, Texas