Since around the 1960s, we've had large economic forces greatly increasing the supply of labor affecting wages:

  1. Women entering the workforce, essentially doubling the labor pool.
  2. Immigration - at least a million a year, every year.
  3. Globalization - instead of local workforce, many companies can now outsource labor to cheaper countries without regulation.
  4. Manufacturing - due to NAFTA, companies who once manufactured in the US can now get much cheaper labor to Mexico. This is related to #3.
  5. Automation - The amount of labor needed to perform a task has been greatly reduced.

To sum it up in my mind, US companies have more or less fixed poverty at a global scale while making a profit at the expense of US workers. #3 and #4 are largely a result of removing tariff and trade regulations. #2 is also a result of government policy. Easing any of these things over decades, one at a time would have been preferred, allowing the economy to adjust. Unfortunately they all happened in a roughly 30 year period between the 1970s and the 2000s, and have accelerated since.