Answer:
The most significant change that has affected US factory workers since 1990 is likely the increased adoption of automation and technology in manufacturing. Automation and technology have led to significant improvements in efficiency, productivity, and quality control in the manufacturing process, but they have also contributed to a decline in manufacturing employment.
With the rise of automation, many routine and repetitive tasks that were previously performed by human workers can now be done by machines. This has led to a decrease in the demand for low-skilled manufacturing jobs, such as assembly line work. At the same time, the demand for workers with advanced technical skills, such as computer programming and robotics, has increased.
The impact of automation on employment has been significant. According to a report by the Center for Business and Economic Research at Ball State University, automation accounted for 85% of the decline in US manufacturing employment between 2000 and 2010. Furthermore, the adoption of automation and technology in manufacturing is likely to continue in the future, which means that the impact on employment is likely to persist.
In summary, the increased adoption of automation and technology in manufacturing is the most significant change that has affected US factory workers since 1990. While this has led to improvements in efficiency and productivity, it has also contributed to a decline in manufacturing employment, particularly for low-skilled workers.