Yes, subduction is the rule rather than the exception.
The western U.S. is the exception rather than the rule, however. most of the
volcanics (and plutonics) south of Shasta are an indirect result of subduction or
melting.
The Pacific plate currently slips along the coast of California on the San
Andreas Fault, but this was not always the case. Much of the Pacific has
actually subducted below the continent of North America. The east-Pacific
rise is the spreading center for the Pacific and is currently located below
the Rocky mountains (in fact in cross-section, the Colorado Rockies look
exactly like a mid-ocean ridge system).
As the Pacific was subducting at a shallow angle, it cause melting of
large amounts of material beneath eastern California and the Basin and
Range Province in Nevada. It is this melted material which makes up the
volcanic provinces in this region, but the subduction itself. It is currently
very difficult to identify a subduction zone under this region, but it is
thought that it must be there because of the strong melting. The temperatures
under this region are much higher than under most continental regions of the
world.