The community was named after Pennsylvania, the Keystone State, the former home of an early postmaster.

[2] Keystone was on the site of the Harriston post office which was in operation from October 12, 1883 to September 22, 1884.

At that time Smith & Sons were the general merchants, the Carmichael Brothers also had a general store and a hotel, E.M. Robish dealt in lumber and fuel, and John W. Smith was a blacksmith, most likely being Keystone’s first postmaster.

In 1883 he came west, first to Oregon and then to Rockford, Spokane County, where he erected the first brick block in that town.

This Adams County, Washington state location article is a stub.