  We report the experimental observation of conductance quantization in
graphene nanoribbons, where 1D transport subbands are formed due to the lateral
quantum confinement. We show that this quantization in graphene nanoribbons can
be observed at temperatures as high as 80 K and channel lengths as long as 1.7
$\mu$m. The observed quantization is in agreement with that predicted by
theoretical calculations.
