About 35.5 million, or 20.0 percent, of the 177.4 million persons 1 year old and over who were living in the United States in March 1961 had move at least once since March 1960. Although this overall mobility rate has reflected to some slight extent some of the postwar chnages in business conditions, it has remained relatively stable in the 14 successive annual surveys conducted since 1948. The percentage of reported movers in the total population 1 year old and over has ranged from 18.6 to 21.0, with an average of 19.7, and has not shown any discernible trend.