Missing millions: the human cost of the Mexican Revolution

© 2001 Robert McCaa, University of Minnesota Population Center


The human cost of the Mexican Revolution (1910-1920) was enormous, but there is little agreement on the magnitude, causes or components of the disaster.  Published census figures for 1910 and 1921 understate the magnitude of the catastrophe because the 1921 count was without doubt the worst conducted in Mexico in the twentieth century.  The “official” loss from a comparison of crude census figures for these years (15.2 million for the former and 14.3 for the latter) is almost one million, around six percent of the population in 1910.  The loss triples when the demographic growth of the decade preceding the outbreak of war is added to the equation.

Losses can be decomposed into excess deaths, lost births, epidemics, emigration and census error.  A new demographic method, inverse projection, is used to read the demographic history of Mexico for the decade of revolution from the age and sex structure of the population in the 1930 censuses of Mexico and the United States.  The best fitting model reveals an undercount in the 1921 census of one million and a total demographic loss from 1910 to 1921 of 2.1 million.  Excess deaths accounted for two-thirds of the missing millions (900 thousand males and 500 thousand females), lost births one-fourth and emigration considerably less than one-tenth of the total (100 thousand male and 75,000 female net persisting emigrant refugees).    These fractions are not original, having been proposed by one or another researcher over the past three-quarters of a century.  What makes them unique, in addition to the breakout by sex, is how they are combined and how they were derived.   For the first time two demographic equations, one for each sex, are tested. As a final test, results from the inverse projection method are compared with those from conventional cohort component projections.  The conventional method permits a rough assessment of the losses in Morelos (where Emiliano Zapata was most active) and for other states of Mexico.