Historical studies dealing with regional statistical comparisons over times do often have to face difficulties of an administrative borders incomparability. For example, Russian population censuses provide a very important historical source on social and economic history, but research of the regional distribution cannot be done directly, because of the massive changes in Russia’s borders, both external and internal. The borders in 1897, 1926, and 1959, when the three first solid censuses had been organized, were completely different, so it was no a region of Russia which stayed exactly with the same territory during any two moments of the three of the censuses. The article argues on the methods which can be used to overcome the problem. We show some examples how a GIS-based approach helps both to recalculate the data to make them compatible and to visualize some data and to facilitate the changing borders issue. The main research goal of the case study is to understand the main patterns of urban development in Russia during the first half of the 20th century.