Trends in Self-Employment among White and Black Men during the Twentieth Century
考察1910至1997年美国白人和黑人男性非农业自雇率的变化，发现自雇率在1970年前下降后回升，黑人自雇率长期仅为白人的三分之一，且行业分布无法解释此差距。
We examine white and black male nonagricultural self-employment from 1910 to 1997. Self-employment rates fell through 1970 and then rose. White male trends were due to declining rates within industries, ending in 1970, counterbalanced by a continuing shift toward high self-employment industries. Social security and immigration do not explain the recent upturn. Black male rates have been roughly one-third of white rates from 1910 to 1997. Blacks are not concentrated in low self-employment rate industries. Absent continuing forces limiting black self-employment, a simple inter-generational model suggests quick convergence of black and white rates.