If you know some figures on returned slaves over time, I'd be interested. Thanks.
I do see the following in The Daily Mississipian newspaper of January 16, 1861:
Washington, Jan. 12. Hon. Wm H. Seward, of New York, addressed the Senate to-day, on the President's message. He said Congress ought, if it can, redress any real grievances of the offended States, and then supply the President with all the means necessary to maintain the Union. He argued that the laws contravening the constitution, in regard to the escape of slaves, ought to be repealed. He was willing to vote for an amendment to the constitution, that Congress should never have the power to abolish or interfere with slavery within the States.He said that he was ready to vote for any properly guaranteed laws to prevent the invasions of the States by citizens of other States. (I think here he was talking about one of the grievances of the Southern states, that people from the North were coming down and invading farms, etc., to take away slaves. I've seen reference to this in some of the secession ordinances. Also, Southerners had been killed in the North trying to get their slaves back, but I don't know how frequent that sort of thing was. Rare probably.)