Shirley Jackson uses the ominous symbol of the "black box" to forshadow the darker meaning of "The Lottery." From as early on in the story as the fourth paragraph, Jackson pays careful attention to the details of the black box.
The reader first sees mention of it as Jackson introduces Mr. Summers who, "carrying the black wooden box" solemnly places it on a wooden stool in the middle of the square. The villagers "kept their distance, leaving a space between themselves and the stool;" this key detail reveals that the black box is somewhat 'viral,' the villagers do not want to get too close as if the danger of the box might be catching, like a disease.
The black box also represents the traditions of the small town, and in that, the box becomes a microcosm of the lottery itself. In no way do the villagers even consider replacing the battered wooden box, because of its traditional value--even though the box is out-dated and no longer really meets their needs...just like the lottery itself. The lottery, like the black box, is a left-over ritual from years past, archaic and wasteful, but the villagers, so entranced by tradition for tradition's sake, cannot see beyond their narrow mindsets to consider doing away with it.