What invention fundamentally unlocked widespread, individualized freedom of movement by allowing travelers to dictate their own itinerary?

Answer

The internal combustion engine powering the automobile

The internal combustion engine powering the automobile is identified as the invention that truly unlocked widespread, individualized freedom of movement because it allowed the traveler to dictate their own itinerary, overcoming the limitations of fixed infrastructure.

What invention fundamentally unlocked widespread, individualized freedom of movement by allowing travelers to dictate their own itinerary?
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