By one estimate, 100,000 slaves escaped from bondage in the South between 1810 and 1850. The southern newspapers almost every day were filled with announcements about new shoots of slaves, for catching of which the big reward was offered. There was even a special detachment of professional hunters for the fugitives who caught them and returned them back to the owner. But if the slave managed to reach the Canadian border, the persecution ceased. That's a rough estimate, but I hope it helps!!!