In this Letter we examine the arrival directions of the most energetic cosmic
rays (E > 2 * 10^19 eV) detected by several air shower experiments. We find
that data taken by different air shower arrays show positive correlations,
indicating a non--uniform arrival direction distribution. We also find that the
events with energy $ > 4 * 10^19 eV exhibit a correlation with the general
direction of the supergalactic plane, where a large number of potential sources
is located. If confirmed by data from other experiments our results would
support models for the extragalactic origin of the highest energy cosmic rays.