Santiago Tapextla is a town and municipality in Oaxaca in south-western Mexico. The municipality covers an area of km². It is located in the Ja…Santiago Tapextla is a town and municipality in Oaxaca in south-western Mexico. The municipality covers an area of km². It is located in the Jamiltepec District in the west of the Costa Region. As of 2005, the municipality had a total population of.