Dallas (WBAP/KLIF) – Southwest Airlines says it will drop its service to Mexico City by the end of March. It says it is doing so to reallocate its resources to better opportunities. The airline says it is gearing up to expand flights to Hawaii. Final government approval for those flights has been delayed by the on-going shutdown. Souithwest says pulling out of Mexico City won’t affect Southwest flights to popular Mexican resort destinations including Cancun, Puerto Vallarta, and Cabo San Lucas.