In this paper there was presented the problem of national identity development in the Eastern Galicia at the turn of the 19th and 20th centuries. The used source materials concerned with thedistribution of population speaking Polish and Ruthenian (Ukrainian) languages and declaring themselves as practising Roman Catholic or Greek Catholic religion within the administrative districts. The data came from the population censuses carried out in the Austro-Hungarian Monarchy in the years 1890, 1900 and 1910. Based on the calibrated maps of the Kingdom of Galicia and Lodomeria and the census data, geostatistical analysis was performed using GIS software. The obtained thematic maps of language and religion distribution in the Eastern Galicia enabled to distinguish the Polish, Polish-Ruthenian and Ruthenian areas. Spatial interpretation of the results was preceded by historical study of the examined area.