Using newly digitized unemployment insurance claims data, we construct historical monthly unemployment series for US states going back to January 1947. We validate our series, showing that they are highly correlated with the Bureau of Labor Statistics' state-level unemployment data, which are only available since January 1976, and capture consistent business cycle dynamics. We use our claims-based unemployment rates to study the postwar evolution of labor market adjustments to local demand shocks and state unemployment fluctuations around national recessions. We document: (1) a trend decrease in the dispersion of relative employment growth and unemployment across states; (2) an attenuation of relative employment, unemployment, and population responses to state-specific demand shocks in recent decades; and (3) a convergence across states in both the speed and degree to which unemployment recovers after recessions. These trends show the emergence of a national business cycle experienced more uniformly across US states, particularly since the 1960s. We present evidence suggesting that a convergence in states' industrial composition helps explain why a more uniform business cycle emerged when it did. And states' increasingly similar experience in recessions may help explain why interstate migration became a weaker adjustment mechanism in recent decades.

使用新数字化的失业保险索赔数据，我们构建了可追溯到 1947 年 1 月的美国各州的历史月度失业率序列。我们验证了我们的系列，表明它们与美国劳工统计局的州级失业数据高度相关，这些数据自 1976 年 1 月以来才可用，并捕捉了一致的商业周期动态。我们使用基于申请人数的失业率来研究战后劳动力市场调整对当地需求冲击和国家经济衰退前后各州失业率波动的演变。我们记录了：（1） 各州之间相对就业增长和失业率的分散性呈下降趋势;（2） 近几十年来，相对就业、失业和人口对各州特定需求冲击的反应减弱;（3） 各州在经济衰退后失业率恢复的速度和程度上趋同。这些趋势表明，美国各州的全国性商业周期的出现更加一致，尤其是自 1960 年代以来。我们提供的证据表明，各州工业构成的趋同有助于解释为什么当它出现时会出现一个更统一的商业周期。各州在经济衰退中越来越相似的经历可能有助于解释为什么近几十年来州际移民成为一种较弱的调整机制。