Who is The Ferryman from A Death in the Family and what is their importance?

When Jay travels to LaFollette in the middle of the night, he has to wake the Ferryman, whose job is to ride cars across the river on his flat ferryboat. The Ferryman is prepared to charge him a double rate but, finding a horse-drawn wagon of people going toward town and paying for the boat's return trip, can only fairly charge the single rate.