The thing that struck me is that the new census data shows a marked shift of population to the South and Southwestern States. Since the House of Repersentitives is based upon the total population (legal, illegal, slave and free) to decide the total 435 seats one possible reason for the population growth in those States, like Texas which will gain 4 additional seats in Congress, is the increase of the Hispanic Population (legal and Illegal) and not migration of people from Northern States, which are losing their repersentation to these states.
Because of the 3/5's law regarding the division of repersentative according to the slave population, with a total population in the 1860 census of 31,000,000 people which included 4,000,000 blacks mostly in the south. would mean that the repersentation apportioned to the Southern States because of the slaves would have been 55 repersentatives. If my figures are correct. 31,000,000 divided by 435 equaling one repersentative for every 71.500 people. 4,000,000 slaves divided by 71,500 equaling 55.
Now remembering that the electorial College vote which elected Lincoln would have been based on the 1850 census in which the "slave" repersentation would have been much less. And that there was a substancial increase in the slave population between 1850 and 1860. What do you think would have been the political effect of this in the northern states?