This paper presents a regional case study using a Bi-Regional Input-Output (BRIO) matrix of Buenos Aires City (BAC) and the Rest of Argentina (ROA), constructed from the Argentinian Input-Output matrix. A hybrid approach was applied to obtain the BRIO matrix, which combines pure non-survey methods with matrix-balancing methods like RAS or Cross-Entropy. Once the BRIO matrix was obtained, our study has focused on analyzing the BAC regional structure and the interconnections between regions. We have also estimated the regional and national carbon footprint for the BAC and Argentina, respectively. Results show that service and industry sectors play an important role in the economy of BAC and some of them have strong interregional spillover effects over the rest of the country. In addition, the results also show that sectors on BAC with the highest regional multipliers are also the ones with highest emissions.