A Road To Prosperity?

There are several ways to bring some manufacturing jobs back to the U.S. 1. Lower U. S. labor costs to match world averages after accounting for transportation costs. 2. Apply a tariff wall that would increase the cost of goods to the consumer by the same amount as the tariff. 3. Apply robotic technology to match or undercut the cost of foreign or domestic labor. Question: Which option would increase the standard of living, for the working class, to 1970 levels?