The Full Story
The Underground Railroad didn't end at the American border. It ended in Canada. British territory, where slavery was illegal and fugitives were free.
Thousands of escaped slaves made the journey north. When they crossed into Canada, they were beyond the reach of American law. The Fugitive Slave Act of 1850 meant nothing on British soil.
American slave catchers followed. They demanded extradition. They claimed these people were property, that Canada was obligated to return them under international law.
British authorities refused. In case after case, Canadian courts ruled that people could not be property. Extradition treaties covered criminals, not victims. The escaped slaves stayed free.
America was outraged. The issue poisoned Anglo-American relations throughout the 1850s. Southern politicians accused Britain of hypocrisy and theft.
Britain didn't budge. Estimates range from 30,000 to 40,000 escaped slaves who found freedom in Canada, around half of them arriving in the 1850s. Every one of them was a person Britain refused to return.
Why This Matters
Canada's role as the terminus of the Underground Railroad was a British policy choice. Britain could have returned fugitive slaves to maintain good relations with America. They chose principle over diplomacy.