Final answer:
The U.S. natural rate of unemployment has declined since the early 1990s due to technological advancements, policy changes, globalization, demographic shifts, and labor market restructuring. After the Great Recession, the rate increased but forecasts predicted a decrease, which materialized; by 2022, the estimated natural rate was 4.6%.
Step-by-step explanation:
The question asks why the U.S. natural rate of unemployment has fallen since the early 1990s. Estimates of the natural rate of unemployment in the early 2000s were about 4.5 to 5.5%, which was lower than earlier estimates. Factors contributing to this decrease include advancements in technology, changes in government policies, globalization, demographics, and changes in the labor market structure. For example, improved technology may have made the matching of workers with jobs more efficient, thus lowering the natural rate.
The Great Recession of 2008-2009 significantly increased unemployment rates, but the unemployment rate was expected to fall by various forecasts, including those from the Congressional Budget Office. Indeed, unemployment rates did decrease, and by 2015, they had returned to about 5%. Later, in the first quarter of 2022, the natural rate was estimated to be 4.6%. Comparatively to other high-income economies, the natural rate of unemployment in the U.S. has been relatively low.