The 1850 census had a dramatic shift in the way information about residents was collected. For the first time, free persons were listed individually instead of by head of household. Two questionnaires were used - one for free inhabitants and one for slaves. The question on the free inhabitants schedule about color was a column that was to be left blank if a person were white, marked "B" if a person were black, and marked "M" if a person were mulatto. Slaves were listed by owner, and classified by gender and age, not individually, and the question about color was a column that was to be marked with a "B" if the slave were black and an "M" if mulatto.