What is promised land in the book Underground to Canada by Barbara Smucker?

In the book "Underground to Canada" by Barbara Smucker, the promised land refers to the state of Ohio in the United States, which was a free state where enslaved individuals could seek freedom. In the novel, the main character, an enslaved boy named Samuel, escapes from slavery in Virginia and travels through the Underground Railroad, a network of secret routes and safe houses, towards Canada, which is also a free territory. However, when he reaches Ohio, he learns that it too is a promised land, as it offers hope and freedom for those who have escaped the brutal institution of slavery.