house ▁and ▁Andrew ▁El lic ott ▁and ▁their ▁crew ▁completed ▁the ▁survey ▁of ▁the ▁Mason – D ixon ▁line ▁to ▁the ▁south west ▁corner ▁of ▁Pennsylvania , ▁five ▁degrees ▁from ▁the ▁Del aware ▁River . ▁Other ▁survey ors ▁continued ▁west ▁to ▁the ▁Ohio ▁River . ▁The ▁section ▁of ▁the ▁line ▁between ▁the ▁south western ▁corner ▁of ▁Pennsylvania ▁and ▁the ▁river ▁is ▁the ▁county ▁line ▁between ▁Marshall ▁and ▁W etz el ▁count ies , ▁West ▁Virginia . ▁ ▁The ▁Mason – D ixon ▁line ▁has ▁been ▁res ur vey ed ▁three ▁times : ▁in ▁ 1 8 4 9 , ▁ 1 9 0 0 , ▁and ▁in ▁the ▁ 1 9 6 0 s . ▁On ▁November ▁ 1 4 , ▁ 1 9 6 3 , ▁during ▁the ▁b ic ent enn ial ▁of ▁the ▁Mason – D ixon ▁line , ▁U . S . ▁President ▁John ▁F . ▁Kennedy ▁opened ▁a ▁newly ▁completed ▁section ▁of ▁Inter state ▁ 9 5 ▁where ▁it ▁crossed ▁the ▁Maryland – Del aware ▁border . ▁It ▁was ▁one ▁of ▁his ▁last ▁public ▁appearances ▁before ▁his ▁assass ination ▁in ▁Dallas , ▁Texas . ▁The ▁Del aware ▁Turn pi ke ▁and ▁the ▁Maryland ▁portion ▁of ▁the ▁new ▁road ▁were ▁later ▁designated ▁as ▁the ▁John ▁F . ▁Kennedy ▁Memorial ▁Highway . ▁ ▁System atic ▁errors ▁and ▁experiments ▁to ▁we igh ▁the ▁Earth ▁Mason ▁and ▁D ixon ▁could ▁only ▁do ▁the ▁work ▁as ▁accur ately ▁as ▁they ▁did ▁due ▁to ▁the ▁work ▁of ▁Ne vil ▁M ask ely ne ,