I'm looking for early uses of 'razorback' in reference to a feral hog. I have numerous examples from the 1890s and a few from the 1880s, but expect it has an earlier etymology. Any help appreciated.

Welcome runnel

OED3 has this for the hog (other senses [e.g., razor-back whale] are earlier):

1845 South. Agriculturist July 258 Razor-back hogs and sway-back cattle, and sheep that dogs will hardly eat after killing.

I know this isn't exactly what you're looking for, but it does give something of a timeline:
Arkansas was known for its razorback hogs long before the University of Arkansas mascot came into being. These wild boars were called razorbacks because of their high, hair-covered backbone and ill-mannered temper. The razorback hog was considered ruthless and dangerous when backed into a corner.

The true wild boar, also called the European or Russian boar, is not native to the United States. Christopher Columbus introduced their domesticated ancestors to the New World in 1493. Wild boars are thought to have arrived with explorer Hernando de Soto, who brought the original thirteen grunting hogs to the new world in 1539

From here

Great reference. I wonder how many states have similar.

Thanks for those suggestions. Appreciate it.