Uruguay, once known as the “Switzerland of South America” for its advanced social and economic development, is a country in which it is surprisingly difficult to obtain statistical data, and quantitative demographic sources are little known and even less analyzed. Despite the fact that, at the turn of the century, Uruguay had a stable government and an advanced social system (the “welfare state” created by the administraciones batllistas), only five general population censuses had ever been taken (1852, 1860, 1908, 1963, 1975), and only the last three are reliable. However, these are not the only sources available, and it is necessary to survey other major existing demographic data, whether published or unpublished.