The stage was set for the African-American migration into Canada in 1772, when England declared that any slave reaching Canadian soil was automatically free. Following the War of 1812, sizable numbers of runaways started to settle in Canada. People began to call it the "Promised Land," a term that came into wider usage after slavery was banned in 1834 throughout the British colonies. Over the next thirty years, between one and two thousand African Americans entered Canada each year.

The passage of the Fugitive Slave Act of 1850 -which gave a slave owner or his appointed agent the authority to retrieve a fugitive even in the North with the assistance of local authorities-- caused many escapees living in the northern states to cross into Canada. According  to the British and Foreign Anti-Slavery Society, within a year of the bill's passage, some five thousand people had emigrated. Among them were free men and women whose very liberty was threatened by kidnappers, who increasingly abducted and sold them South; and others who felt they were not completely free.

Advocates of immigration to Canada included Abraham Shadd, a free black shoemaker who aided fugitives in Delaware and Pennsylvania during the 1830s and 1840s before settling in Toronto in 1851. His daughter, Mary Ann Shadd, opened a school for fugitive children and edited the Provincial Freeman. She was the first black woman in North America to found and edit a weekly newspaper.

Most runaways settled in what are now the Ontario Province cities of Toronto, Chatham, London, and Windsor; in rural areas along lakes Erie and Ontario; and in the all-black communities of Dawn, Wilberforce, Dresden, and Buxton .

A North-Side View of Slavery. The Refugee, or The Narratives of Fugitive Slaves in Canada, Related by Themselves: With an Account of the History and condition of the Colored Population of Upper Canada. by Drew, Benjamin

In 1837, Joseph Taper and his family fled from Frederick County, Virginia, "in consequence of bad usage." While staying in Pennsylvania, he read a runaway notice in a newspaper calling for his apprehension. Later, in Pittsburgh, he learned of the presence of a slave catcher. Taper took his family to St. Catharines, Ontario, where he rented a farm and settled in raising crops and livestock. In 1840, he wrote to a friend back in Virginia:

"Since I have been in the Queen's dominions I have been well contented, Yes well contented for Sure, man is as God intended he should be. That is, all are born free & equal. This is a wholesome law, not like the Southern laws which puts man made in the image of God on level with brutes ... I have enjoyed more pleasure with one month here than in all my life in the land of bondage."

Teenager Henry K. Thomas fled in 1836 from Nashville, Tennessee. His mother planned his escape after she found out he was slated to be sold. Thomas made his way across middle Tennessee into Kentucky. He was captured and jailed in Louisville, just short of reaching the Ohio River. That night, although shackled, he broke out of jail, stole a small boat, and navigated over the waterfalls to the Ohio shore, where a man removed his chains. By 1850, Thomas was living in Buffalo, New York, as a  property-owning free man. Learning of the Fugitive Slave Act, he took his family across the border, settling in the town of Buxton where he purchased a farm. By the eve of the Civil War, perhaps thirty thousand fugitives lived in Canada.