The 1960 Census of Population is providing a vast amount of detailed statistics reflecting the widespread redistribution of the population during the 1950's. The pattern of population movement during the 1950's parallels, to a great extent, that which occurred during the 1940's, particularly after World War II. To permit better understanding of the population movement, that has occurred from 1950 to 1960, the Bureau of the Census has undertaken the compilation of statistics on the separate components of population change for counties. This is the first time that, estimates of net migration have ever been published for all the counties in the United States. By combining groups of counties into certain widely used statistical areas, such as the standard metropolitan statistical area, State economic area, and economic subregion, one can obtain a broader picture of population movement in the United States.

This report presents estimates of the components of population change in the population of the United States, 1950 to 1960, for counties and standard metropolitan statistical areas (SMSA's), State economic areas (SEA's), and economic subregions.¹ Included are births, deaths, and net total migration. Comparable estimates of net total migration for 1940 to 1950, as derived from the estimates published by Bogue,² are included in tables containing data for State economic areas, standard metropolitan statistical areas and economic subregions.

Estimates of the components of population change in the civilian population for the 1850 decade are also presented in full for State economic areas. Included are births, civilian deaths, net loss to the Armed Forces, and net civilian migration. For counties, net civilian migration estimates are also included.

The two major components of population change for any area are natural increase and net migration. Natural increase represents the difference between the number of births and deaths. Net migration represents the difference between the number of persons migrating into a particular area and the number migrating from the area. It comprises, therefore, both net immigration from abroad and net internal migration. A positive migration figure indicates net in-migration to the area; a negative figure indicates net out-migration from the area. Net total migration includes the movements of Armed Forces whereas net civilian migration excludes these movements.

Another factor in population change—annexation of territory (or boundary change)—is largely inapplicable at the area levels covered in this report, but it may be an important factor in population change for a few counties as well as most of the independent cities in Virginia, which are here treated as county equivalents. For further discussion of this point, see the section "Adjustment of data for changes in county boundaries," page 12.

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¹ See Donald J. Bogue and Calvin L. Beale, Economic Areas of the United States, New York, the Free Press of Glencoe, Illinois, 1961; U.S. Bureau of the Census, State Economic Areas: A Description of the Procedure Used in Making a Functional Grouping of the Counties of the United States, by Donald J. Bogue, Washington, U.S. Government Printing office, 1951; and U.S. Bureau of the Census and Bureau of Agricultural Economics, Farm Population, Series Census-BAE, No. 19, "Economic Subregions of the United States," by Donald J. Bogue and Calvin L. Beale, June 1953.
² Donald J. Bogue, Components of Population Change, 1940–50: Estimates of Net Migration and Natural Increase for Each Standard Metropolitan Area and State Economic Area, Scripps Foundation for Research in Population Problems, Miami University (Oxford, Ohio), and Population Research and Training Center, University of Chicago, 1957.