In new york, there was a great danger to escaping slaves. Why?

New York was filled with people waiting to sanction escaped slaves.

Our knowledge of the north did not extend farther than New York; and to go there, and be forever harassed with the frightful liability of being returned to slavery—with the certainty of being treated tenfold worse than before—the thought was truly a horrible one, and one which it was not easy to overcome. The case sometimes stood thus: At every gate through which we were to pass, we saw a watchman—at every ferry a guard—on every bridge a sentinel—and in every wood a patrol. We were hemmed in upon every side.