Hollerith's idea of punching holes in cards to represent data came from the railroad industry. In Hollerith's time, the railroad issued tickets to passengers with physical descriptions of a passenger's hair and eye color. Conductors punched holes in the ticket to indicate that the passenger's hair and eye color matched those of the ticket owner. From this, Hollerith got the idea of making a punched "photograph" of every person to be tabulated for the census.