Intergenerational Occupational Mobility in Great Britain and the United States Since 1850: Comment. Alexandra Killewald, August 2013, Paper. "Using historical census and survey data, Long and Ferrie (2013) found a significant decline in social mobility in the United States from 1880 to 1973. We present two critiques of the Long-Ferrie study. First, the data quality of the Long-Ferrie study is more limiting than the authors acknowledge. Second, and more critically, they applied a method ill-suited for measuring social mobility of farmers in a comparative study between 1880 and 1973..." Link