Incidents in the Life of a Slave Girl is set in pre-Civil War America, prior to the abolition of slavery. Much of the book takes place in South Carolina, where slavery was legal. The end of the book takes place in the North (Philadelphia and New York), where it had been illegal to enslave people for many years.
The book contrasts the conditions in the North with the conditions in the South. For instance, the South has such brutal conditions for enslaved people that Linda is willing to live in a claustrophobic garret room in Grandmother's shed for seven years so that she might eventually escape to the North. In particular, the South represents the threat of sexual abuse and family separation. Over and over again, families are torn apart when their enslavers sell them, kill them, or drive them to run away. Over and over, sexual abuse entangles Black and white families in traumatic ways. Jacobs uses anecdotes from her own life to paint a picture for Northern readers of an unimaginably cruel Southern social landscape.
The North, on the other hand, represents freedom and the possibility that a Black family can be together again, if only they can all get there. But as the book goes on, the difference between the North and the South becomes less pronounced. Although Linda is reunited with her son and daughter in the North, going there is also a letdown. It turns out that the North is not so free of the horrors of enslavement as people might like to think (especially the people who live there).
The Fugitive Slave Law of 1850 does a great deal to break down the fragile boundary between the North and the South. Jacobs started to write her memoir in 1853, and part of what it captures is the way this new law sullied the promise of the North not only for enslaved and formerly enslaved Black people, but for everyone else as well. The law made it a crime in Northern states to help Black people who had escaped enslavement in the South. It also made the federal government responsible for the cost to enslavers of finding those who had escaped and kidnapping them back into enslavement. In the memoir, this means that until a white woman buys Linda's freedom, there is hardly any legal difference in Linda's status whether she is in a Northern or Southern state.
This let-down is important to the book as an attempt to persuade Northerners that abolition is not just a Southern issue. Still, the memoir makes it clear that any degree of freedom is better than enslavement. Despite the many disappointments of the North, Linda still finds greater opportunity there to work for her own living and to engage in mutually supportive communities across racial lines.