The national statistics system presents a remarkable flaw: there is no set of indicators that allows a homogeneous comparison of the economic performance of the 24 Argentinean provinces. The Provincial Activity Composite Index (ISAP) intends to fill that void. It consists of a system of 25 coincident indicators (one for each province and one for the country level) whose variations are obtained as a weighted mean of the variations of several variables that strongly correlate to the economic performance. In this presentation, we review the existing literature on the subject, deeply describe the methodology used and present our results. ISAP becomes a very relevant tool for provincial economic monitoring, as well as for design and assessment of specific policies for each province. Moreover, the flexibility of this methodology allows for replicability in other countries that lack this kind of information.