This paper offers a review of history of education statistics in Spain, starting in the mid-nineteenth century, describing their traditional means of operation based on censuses, flat tables, and macro-statistical data, which usually display a purely quantitative analysis. Only in recent decades have statistical analyses appeared, supported by modern office tools and parametric data processing, which facilitate qualitative research. Among other types of graphics used, for our purposes those based on serial mapping are especially revealing and useful, as they show the diachronic evolution of the variables analysed. Supported by this methodology, the present study statistically analyses the official data on state primary education in Extremadura in the second half of the nineteenth century, in order to demonstrate how significant the increase in financial investment in the late nineteenth century was and its direct impact on expanding the coverage of the educational network at a regional level. That meant the disappearance of inequalities in all educational standards (school equipment, number of appointments, salaries, gender, etc.) and, therefore, a reduction in illiteracy rates.