▁construction ▁of ▁Six ▁Fl ags ▁Over ▁Texas . ▁At ▁the ▁end ▁of ▁ 1 9 7 7 , ▁the ▁b onds ▁were ▁paid ▁off ▁and ▁the ▁fre ew ay ▁was ▁handed ▁over ▁to ▁the ▁state ▁Department ▁of ▁Transport ation , ▁to ll ▁collection ▁ceased , ▁and ▁the ▁to ll bo oth s ▁were ▁removed ▁in ▁the ▁first ▁week ▁of ▁ 1 9 7 8 . ▁ ▁It ▁served ▁as ▁I - 2 0 ▁between ▁Dallas ▁and ▁Fort ▁W orth ▁until ▁the ▁current ▁I - 2 0 ▁route ▁to ▁the ▁south ▁was ▁opened ▁in ▁ 1 9 7 1 . ▁After wards , ▁I - 3 0 ▁was ▁extended ▁from ▁its ▁end ▁at ▁the ▁" D allas ▁Mix master " ▁inter change ▁with ▁I - 3 5 E ▁( also ▁the ▁east ▁end ▁of ▁the ▁turn pi ke ) ▁to ▁follow ▁the ▁turn pi ke , ▁and ▁the ▁former ▁I - 2 0 ▁in ▁dow nt own ▁Fort ▁W orth , ▁west ▁to ▁modern - day ▁I - 2 0 . ▁ ▁The ▁existing ▁US   6 7 ▁route ▁was ▁already ▁in ▁heavy ▁use ▁in ▁the ▁early ▁ 1 9 5 0 s , ▁at ▁which ▁point ▁it ▁was ▁tw inned ▁from ▁just ▁east ▁of ▁Dallas ▁to ▁Rock wall ▁and ▁also ▁near ▁Green ville . ▁The ▁D F W ▁Turn pi ke ▁linking ▁Fort ▁W orth ▁to ▁Dallas ▁was ▁completed ▁by ▁ 1 9 5 7 , ▁becoming ▁the ▁first ▁segment ▁of ▁I - 3 0 . ▁The ▁tw inned ▁US   6 7