Washington DC held the distinction of being home to the largest slave market in the country before the war for Southern Independence. (According to PBS). 

Congressman Daniel Gott's resolution of December 21, 1848 would have abolished slavery in Washington DC had it passed the House of Representatives. Illinois Congressman Lincoln sided with pro-slavery members and voted against the resolution. HUarchivesNet the Electronic journal MSRC Howard University…also Lerone Bennett “Forced into Glory”

Congress did pass the DC Emancipation Act in 1862, but Lincoln delayed signing for 48 hours to give his old friend from Kentucky time to get out of town with his slaves…The Act also called for the immediate expulsion of all freed slaves from the city and set aside funds for their colonization (deportation)…(Lochlainn Seabrook, “Everything…” p. 153)

Twenty months later (Dec 1863) the administration was still using slave labor to complete construction of the Capitol Building in DC…

Considering that Northerners (along with Europeans) imported all the slaves into this country, should the North not bear some responsibility for slavery in America? NAW, IT'S EASIER TO DEMONIZE THE SOUTH AND RE-WRITE HISTORY...TO GLORIFY A TYRANT.