100 Years of Rising Corporate Concentration
利用美国企业规模分布百年数据，发现生产集中度（如头部企业资产或销售份额）持续上升，1970年前后行业重点从制造业转向服务业等。
We collect data on the size distribution of US businesses for 100 years, and use these data to estimate the concentration of production (e.g., asset share or sales share of top businesses). The data show that concentration has increased persistently over the past century. Rising concentration was stronger in manufacturing and mining before the 1970s, and stronger in services, retail, and wholesale after the 1970s. The results are robust to different measurement methods and consistent across different historical sources. Our findings suggest that large firms have become more important in the US economy for a long period of time.