According to estimates from the Current Population Survey conducted by the Bureau of the Census, 17.9 percent of the 201,506,000 persons 1 year old and over living in the United States in March 1971 had moved within the country during the preceding twelve months. This 17.9 percent represents about 36,161,000 persons, with 23,018,000 moving within counties and 13,143,000 moving between counties. An additional 1,544,000 persons had been living abroad in March 1970. Inclusion of these movers from abroad reveals that about 18.7 percent of the March 1971 United States poplulation 1 year old and over had been living at a different address one year earlier. With the exception of persons who moved from, but returned to, their 1970 address during the survey year, the survey provides an estimate of all persons who moved during the year. It does not, however, provide an estimate of the total number of moves during the year, since the movers may have moved mroe than once.