The book begins in the mid-19th century on the Shelby plantation in Kentucky, where Uncle Tom lives in a cabin with his wife and children. After fellow slave Eliza, the "favorite" of Mrs. Shelby, learns that her son is being sold, she flees north up through Ohio and on to Canada with her husband, also an escaped slave.
Although in 1852 the northern states were "free states," thanks to the Fugitive Slave Act of 1850, masters could track down runaway slaves in the north, recapture them, and send them south. Canada, as part of the British Commonwealth, which had abolished slavery in all of its territories by 1834, could provide protection for refugee slaves crossing its southern borders. The movement of George and Eliza from Kentucky through Ohio to Canada is, therefore, not only a geographical trajectory; it also represents a shift from danger into safety.
By contrast, of course, is Tom’s journey from (relative) north, in Kentucky, south to New Orleans. After a peaceful sojourn in the lush and beautiful St. Clare plantation, Tom’s move to the isolated and desolate Deep South under the power of Simon Legree represents both a spatial and narrative transition down into darkness and danger.
Of course, Stowe’s delineation of the North and South isn’t really this simplistic: the North is still pretty racist (as we can see from Miss Ophelia) and the South gives birth to the most Christ-like character in the novel, Eva. For more on the complexities of the North and South settings, see our analysis under "Symbols, Imagery, Allegory."