In what time period does the novel, The Underground Railroad, take place?

The novel is set in the early 1800s, a period where the slave trade, and the building of the American economy on that trade, was close to, or at, its peak. It is also the period when divisions between the Northern states (in which slavery was rejected) and the Southern (in which slavery was regarded as not only essential, but morally and Biblically correct) started to become more and more apparent.