John Hope Franklin and Loren Schweninger, Runaway Slaves: Rebels on the Plantation (New York: Oxford University Press, 1999), 367n.
Estimates of the number of slaves who made it to freedom in the North vary considerably. It is probable, however, that perhaps one or two thousand per year were successful during the post-1830 period. Not all of them traveled along the routes of the Underground Railroad, however. Whatever the exact number, it is clear that the fugitives who made it to freedom in this manner represented, as one historian said, a “mere trickle from among the millions of slaves.” By contrast, tens of thousands of slaves ran away each year into the woods, swamps, hills, backcountry, towns, and cities of the South. Indeed, running away in the South was commonplace.