During the post World War II years and through the 1960s, the Mexican economy underwent strong and sustained growth that was accompanied by internal and external stability. This expansion was fueled by major increases in agricultural production, by industrializa? tion caused by import substitution, and by an active government policy of investment in infrastructure. [Reynolds, 1970] From 1960 to 1970 real gross domestic product grew at an average annual rate of 7.0 percent, per capita income increased by 40.7 percent, and inflation averaged only 3.5 percent per year. This growth was accompanied by structural change. The portion of gross domestic prod? uct (GDP) derived from agriculture declined 7.2 percent as this sector entered a slump during the middle of the decade. In contrast, the contributions to GDP of the manufacturing, commercial, and service sectors rose. The labor force in agriculture decreased from 54.2 percent to 39.4 percent. Moreover, major population shifts from rural to urban areas occurred: by 1970 58.5 percent of Mexico's population lived in urban areas, compared to 50.7 percent in 1960. Significant interstate migration also took place, especially towards the capital city and the northern border states. Changes of these magnitures may be expected to give rise to signifi? cant alterations in the distribution of Mexican income at the regional level, which is the focus of this study. Empirical evidence suggests that changes in the size distribution of income have accompanied Mexican economic growth. The information comes from a series of data sets, beginning with the benchmark J950 General Population Census. Later data are available from the 1960 and 1970 censuses, as well as from income and expenditure surveys undertaken in 1958, 1963, 1975, and 1977. [Mexico, 1956, 1960, 1975, 1979; Banco de Mexico, 1966, 1973] Although serious problems abound in making direct comparisons between measures obtained from the different data sources, especially