Blackwell was born U. Z. Brown on March 18, 1933, in Lula, Mississippi, to sharecroppers Virda Mae and Willie Brown. Blackwell's uncle gave her the name "U. Z.", which she kept until she was in the sixth grade, when her teacher told her that she needed "a real name, not just initials". Blackwell and her teacher decided on Unita Zelma.
Blackwell and her parents lived in Lula. Her grandfather had been murdered by a white plantation boss. In 1936, when she was three years old, Blackwell's father left the plantation on which he worked and fled to Memphis, Tennessee, fearing for his life after he confronted his boss about speaking to his wife. Blackwell and her mother left the plantation to live with him soon afterward. Blackwell's family traveled frequently in search of work. On June 20, 1938, Blackwell's parents separated due to religious differences. Blackwell and her mother went to West Helena, Arkansas, to live with Blackwell's great aunt so that she had the opportunity to receive an education. A quality education in Mississippi was not an option for Blackwell because the schools there were centered on the cultivation of crops and the plantation system. Black children were allowed to attend school for only two months at a time, before they were expected to go back to the cotton fields. While living in West Helena, Blackwell often visited her father in Memphis. During the summer months she would leave West Helena and live with her grandfather and grandmother in Lula, where she helped plant and harvest cotton. Blackwell spent a majority of her early years chopping cotton for $3 a day, in Mississippi, Arkansas, and Tennessee as well as peeling tomatoes in Florida. She was 14 when she finished the eighth grade, the final year of school at Westside, a school in West Helena for black children. Blackwell had to quit school to earn for her family.
Marriage and move
She was 25 when she first met Jeremiah Blackwell, a cook for the U.S. Army Corps of Engineers. A few years later, they traveled to Clarksdale, Mississippi, and were married by a justice of the peace.
In January 1957, Blackwell became extremely ill and was taken to the hospital in West Helena where she was pronounced dead. She was later found to be alive in her hospital room, and claims to have had a near-death experience. On July 2, 1957, the couple's only son, Jeremiah Blackwell Jr. (Jerry), was born. In 1960, Jeremiah's grandmother, "Miss Vashti", died. A few months later, the Blackwells moved into the shotgun house that his grandmother had left to him, in Mayersville, Mississippi, a town of nearly five hundred people. The Blackwell family eventually was able to build a larger brick home, but she wanted to keep the smaller house inherited from Jeremiah's grandmother.
I am grateful for this house ... I kept it because it reminded me of where I came from.
After settling in Mayersville, Blackwell began to get involved in the Civil Rights Movement.