▁corner ▁of ▁Pennsylvania , ▁Maryland , ▁and ▁Del aware , ▁at ▁The ▁W edge ▁is ▁marked ▁by ▁B ound ary ▁Monument   # 8 7 . ▁The ▁marker ▁" MD P ▁Cor ner " ▁dates ▁from ▁ 1 9 3 5 ▁and ▁is ▁offset ▁on ▁purpose . ▁ ▁Do yle ▁said ▁the ▁Maryland – P en nsylvan ia ▁Mason – D ixon ▁line ▁is ▁exactly : ▁▁▁▁▁▁▁▁▁▁▁▁ 3 9 ° 4 3 ′ 1 9 . 9 2 2 1 6 ″   N ▁ ▁and ▁B ound ary ▁Monument ▁# 8 7 ▁is ▁on ▁that ▁parallel , ▁at : ▁▁▁▁▁▁▁▁▁▁▁ 0 7 5 ° 4 7 ′ 1 8 . 9 3 8 5 1 ″   W . ▁ ▁Vis itors ▁to ▁the ▁tri point ▁are ▁strongly ▁encourag ed ▁to ▁first ▁obtain ▁permission ▁from ▁the ▁nearest ▁land owner ▁or ▁use ▁the ▁path ▁from ▁the ▁arc ▁corner ▁monument , ▁which ▁is ▁border ed ▁by ▁Del aware ▁park land ▁most ▁of ▁the ▁way , ▁and ▁Pennsylvania ▁park land ▁the ▁entire ▁way . ▁ ▁History ▁▁ ▁The ▁line ▁was ▁established ▁to ▁end ▁a ▁boundary ▁dispute ▁between ▁the ▁British ▁colon ies ▁of ▁Maryland ▁and ▁Pennsylvania / Del aware . ▁Maryland ▁had ▁been ▁granted ▁the ▁territory ▁north ▁of ▁the ▁Pot om ac ▁River ▁up ▁to ▁the ▁for ti eth ▁parallel . ▁Pennsylvania ' s ▁grant ▁defined ▁the ▁col ony ' s ▁southern ▁boundary ▁as ▁following ▁a ▁ 1 2 - mile ▁( radius ) ▁circle ▁() ▁counter - clock wise ▁from ▁the ▁Del aware ▁River ▁until