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.
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.
