Importation was banned in 1810 or so. As for those leaving, some allowance should be made, since many were here involuntarily and some provisions should be made for their return to Africa South America, where ever they came from. For those here now and chose to stay, it's obvious they're happy and lying about hating the place. As for those crying and whining yet refuse to leave, deportation was also an option the Founders resorted to, and that went for 'citizens' as well as noncitizens.