Idaho Transfer (1973)

During a time of waning global resources, a crew of young researchers travel into the future to escape an apocalypse before the shutdown of their time transfer project. They find that some type of disaster has de-populated the Idaho region and, by implication, the nation or perhaps the world. Facing an unknown, barren future of abandoned towns and deserted vehicles; void of radio signals or any signs of air or land traffic, they encounter an abandoned freight train filled with bagged bodies. Their further discoveries of humanity's future fate is somewhat less than rosy. They also learn their time travel was not without significant costs to their own health. After one of the group travels further into the future, she encounters a family in a futuristic automobile; implying humankind has recovered from the disaster (or have they?)