The natural rate of unemployment, or u-star, is used by economists and policymakers to help assess the overall state of the labor market. However, the natural rate is not directly observable and must be estimated. A new statistical approach estimates the natural rate over the past 100 years. Results suggest the natural rate has been remarkably stable over history, hovering between 4.5 and 5.5% for long periods, even during the Great Depression. Recent readings on the unemployment rate have been running slightly below the natural rate estimate.