▁latitude ▁ ▁south ▁of ▁the ▁southern most ▁house ▁in ▁Philadelphia ▁( on ▁what ▁is ▁today ▁South ▁Street ). ▁As ▁part ▁of ▁the ▁settlement , ▁the ▁Pen ns ▁and ▁Cal ver ts ▁commission ed ▁the ▁English ▁team ▁of ▁Charles ▁Mason ▁and ▁Jer em iah ▁D ixon ▁to ▁survey ▁the ▁newly ▁established ▁boundaries ▁between ▁the ▁Province ▁of ▁Pennsylvania , ▁the ▁Province ▁of ▁Maryland , ▁and ▁Del aware ▁Col ony . ▁ ▁In ▁ 1 7 7 9 , ▁Pennsylvania ▁and ▁Virginia ▁agreed ▁" To ▁extend ▁Mason ' s ▁and ▁D ixon ' s ▁line , ▁due ▁west , ▁five ▁degrees ▁of ▁longitude , ▁to ▁be ▁computed ▁from ▁the ▁river ▁Del aware , ▁for ▁the ▁southern ▁boundary ▁of ▁Pennsylvania , ▁and ▁that ▁a ▁mer id ian , ▁drawn ▁from ▁the ▁western ▁extrem ity ▁there of ▁to ▁the ▁northern ▁limit ▁of ▁the ▁said ▁state , ▁be ▁the ▁western ▁boundary ▁of ▁Pennsylvania ▁for ▁ever ." ▁ ▁After ▁Pennsylvania ▁abol ished ▁sla very ▁in ▁ 1 7 8 1 , ▁the ▁western ▁part ▁of ▁this ▁line ▁and ▁the ▁Ohio ▁River ▁became ▁a ▁border ▁between ▁slave ▁and ▁free ▁states , ▁with ▁Del aware ▁retain ing ▁sla very ▁until ▁the ▁Th ir teenth ▁Am end ment ▁was ▁rat ified ▁in ▁ 1 8 6 5 . ▁ ▁Geography ▁of ▁the ▁line ▁ ▁Mason ▁and ▁D ixon ' s ▁actual ▁survey ▁line ▁began ▁to ▁the ▁south ▁of ▁Philadelphia , ▁Pennsylvania , ▁and ▁extended ▁from ▁a ▁benchmark ▁east ▁to ▁the ▁Del aware ▁River ▁and ▁west ▁to ▁what ▁was ▁then ▁the ▁boundary ▁with ▁western