Formal records stating when conjugal visits began at MSP do not exist; Mississippi was the first state to allow conjugal visits to take place in its prisons. Columbus B. Hopper, author of "The Evolution of Conjugal Visiting in Mississippi" (1989), said "In all probability, conjugal visiting began as soon as Parchman Plantation was made into a prison in 1900" and "I traced it back definitely as early as 1918." There was no state control or legal status for conjugal visits. Originally only African-American men were allowed to participate, as society believed that the sexual drives of black men were stronger than those of white men. Prison authorities believed that if black men were allowed to have sexual intercourse, they would be more productive in the farming industries of the prison. By the 1930s, the authorities had permitted white men to receive conjugal visits. Because the officials did not want pregnancies to occur in prison, at that time they did not permit female prisoners to have conjugal visits. In the 1930s, on Sunday afternoons, prostitutes visited Parchman and the prison camps. Hopper said that a prisoner's song referred to a prostitute charging 50 cents for her services, "not a small amount during the Great Depression when many people worked a 12-hour day for a dollar."