Unión Hidalgo is a town and municipality in Oaxaca in south-western Mexico.

It is part of the Juchitán District in the west of the Istmo de Tehuantepec region.

[1] The municipality covers an area of 132.69 km2 at an average height of 20 meters above sea level.

Flora include Guanacaste, mesquite, cactus, fruit trees (mango, tamarind, coconut, papaya) and pastures.

Wild fauna includes Coyote, skunk, armadillo, badger, rabbit, dove, quail, rook and iguana.