The life expectancy at birth in such countries as the Netherlands, Switzerland and New Zealand is slightly greater than that in the United States. In several of our Northern states, however, the figures reflect a better experience than that recorded in most foreign countries. The explanation appears to lie in the much lower life expectancy among Negroes, a fact which tends to distort the conclusions which might be drawn from examination of only the comparative gross statistics. There is no doubt, therefore, that the life expectancy of the white population of the continental United States is as long as or longer than that of any other country in the world, although that of Negroes is disturbingly out of proportion.
The control of the communicable diseases has been the most important factor in increasing average longevity; in fact, except for tuberculosis and for pneumonia, all the other infections have been almost