Complex sentence: The highway was rerouted to assume MT 34 in the early 1960s and was removed from the cross-state corridor, along which it was mostly replaced by US 287, in the mid- 1960s.
Split into simpler sentences: The highway was rerouted in place of MT 34 in the early 1960s. MT 287 was replaced by US 287 along much of the cross-state corridor in the mid- 1960s.