A map of the United States showing the increase in population per state between the 1900 and 1910 census. The map is keyed to show State population increases ranging from under 2 per cent to 50 per cent and over. "This is a map classifying states with respect to the percentage of increase of population between twelfth and thirteenth censuses. The greatest growth has been in the central and western states, where the increase has been unusually large. This is due to the fertility of the soil in the Mississippi Valley and the opportunities and advantages offered by a new country." - Foster, 1921.