  We study the nuclear ($A$) dependence of the European Muon Collaboration
(EMC) effect at high values of $x$ ($x \geq 0.6$). Our approach makes use of
conventional nuclear degrees of freedom within the Relativistic Impulse
Approximation. By performing a non-relativistic series expansion we demonstrate
that relativistic corrections make a substantial contribution to the effect at
$x \gtrsim 0.6$ and show that the ratio of neutron to proton structure
functions extracted from a global fit to all nuclei is not inconsistent with
values obtained from the deuteron.
