Getting to Oaxaca
Oaxaca has a small international airport located about 20 minutes south of the city center. The bulk of its flights are domestic, though there is a direct flight from Houston, Texas. Your best bet is to fly into Mexico City's airport and hop on either a national flight or a bus to Oaxaca.
Oaxaca's main bus station, the Terminal Central de Primera Clase (address: Avenida Niños Héroes de Chapultepec 1036), is located in the northern part of the city. There are upwards of 50 buses per day to Mexico City, not to mention a slew of other regional and national destinations.