Temporary excess productivity can linger a very long time and sector-specific excess productivity can still be broadly damaging. Detroit and southeastern Michigan were devastated by the collapse of American automotive industry in the '00s, taking something like 10-15 years before starting to recover.
That collapse happened in the late 1970s. And many would debate if its recovered to this day.
Michigan was doing okay until around the late 1990s. The real downslide started out after that; Detroit became the largest municipal bankruptcy in U.S. history in 2013.