The Mexican government studies the possibility of building a new international airport (NAICM) in ZFLT or Tizayuca. The aim of this paper is to determine which the best location site of the NAICM is (ZFLT or Tizayuca) considering the maximization of the sum of expected air pax demand as main factor. To solve such problem, we propose: a mathematical formulation with the objective of maximizing the sum of expected air pax demand and a methodology to estimate air pax demand at each demand point based on an index to measure wealth. Results indicate that Tizayuca is the place where the NAICM should be located for a catchment area smaller than 500km or 4 hours travel time, and ZFLT is the place where the NAICM should be constructed for a catchment area longer than 500km or 4 hours travel time.