Judging from the evidence, from the head down.
Local scavengers normally seem to find roadkill snakes quite a delicacy; they don’t usually stay in place long. But this one has been in T&S’s driveway since last Sunday. It moves around but it never vanishes, and every day there’s a little less of it.
I finally got tired of stepping over it and flipped it over the rock wall. Should have thought to stretch it out and measure it against my 5-foot stick – I’d estimate this as 3-4 feet originally, which isn’t especially big for a bull snake. They have a very bad habit of sunning in the middle of roads, where they look like fallen sticks till it’s too late to swerve safely.