  We have analyzed the clustering of C IV and Mg II absorption-line systems on
comoving scales from 1 to 16 \hMpc, using an extensive catalog of heavy-element
QSO absorbers with mean redshift 2.2 (C IV) and 0.9 (Mg II). For the C IV
sample as a whole, the absorber line-of-sight correlation function is well fit
by a power law of the form $\xi(r)=(r_0/r)^\gamma$, with maximum-likelihood
values of $\gamma = 1.75 ^{+0.50}_{-0.70}$ and comoving $r_0 = 3.4
^{+0.7}_{-1.0}$ \hMpc ($q_0=0.5$). This clustering is of the same form as that
for galaxies and clusters at low redshift, and of amplitude such that absorbers
are correlated on scales of clusters of galaxies. We also trace the evolution
of the mean amplitude $\xi_0(z)$ of the correlation function from $z=3$ to
$z=0.9$. We find that, when parametrized as $\xi_0(z)\propto
(1+z)^{-(3+\epsilon)+\gamma}$, the amplitude grows rapidly with decreasing
redshift, with maximum-likelihood value for the evolutionary parameter of
$\epsilon = 2.05 \pm 1.0$. The rapid growth seen in the clustering of absorbers
is consistent with gravitationally induced growth of perturbations.
