Gintautas Gaidamavicius sent me a link to a document that seems to be available only on the Internet Archive. Its title is "Circoscrizioni Statistiche", published by Istituto Centrale di Statistica in August 1958. With admirable thoroughness, it divides Italy into 10 regioni statistiche plus Rome, where each statistical region consists of one or more historical regions; 92 province; over 300 settori statistici; perhaps 1,000 regioni agrarie; and the thousands of comuni. Cutting across these are 5 zone altimetriche. It shows clearly how they relate to each other, and gives populations and areas down to the regione agraria level. Do these all still exist? A search for settori statistici nowadays turns up nothing geographic, but only economic sectors. Some provinces, at least, have regioni agrarie. A spot-check of Benevento shows that there are now 6 regioni agrarie in the province as compared to 5 in the 1958 document, but most of them have similar names.
