  We study the effects of the symmetry energy on the neutron drip density and
properties of nuclei in neutron star crusts. The nonuniform matter around the
neutron drip point is calculated by using the Thomas--Fermi approximation with
the relativistic mean-field model. The neutron drip density and the composition
of the crust are found to be correlated with the symmetry energy and its slope.
We compare the self-consistent Thomas--Fermi approximation with other
treatments of surface and Coulomb energies and find that these finite-size
effects play an essential role in determining the equilibrium state at low
density.
