  A numerical study is made of current distributions in finite-width Hall bars
with disorder and some theoretical observations are verified. The equilibrium
current and the Hall current are substantially different in distribution. It is
observed that in the Hall-plateau regime the Hall current tends to concentrate
near the sample edges while it diminishes on average in the sample interior as
a consequence of localization. The edge states themselves scarcely affect both
the equilibrium and Hall currents in the plateau regime. The sample edge
combines with disorder to efficiently delocalize electrons near the edge while
the Hall field competes with disorder to delocalize electrons in the sample
interior. A possible mechanism is suggested for the breakdown of the quantum
Hall effect.
