Topography of the Isthmus of Tehuantepec, Mexico17.6N 94.9W
This wide-swath ASAR image shows the Isthmus of Tehuantepec, an isthmus in Mexico that represents the shortest distance between the Gulf of Mexico and the Pacific Ocean. The isthmus includes the part of Mexico lying between the 94th and 96th meridians west longitude, or the southeastern parts of Veracruz and Oaxaca, including small areas of Chiapas and Tabasco. The states of Tabasco and Chiapas are east of the isthmus, with Veracruz and Oaxaca on the west.
At its narrowest point, the isthmus is 200 km (120 mi) across from gulf to gulf or 192 km (119 mi) to the head of Laguna Superior on the Pacific coast. The Sierra Madre breaks down at this point into a broad, plateau-like ridge. The northern side of the isthmus is swampy and densely covered with jungle. Visible in the upper right quadrant is the Términos Lagoon.
The Sierra Madre de Oaxaca mountains flatten out to form Chivela Pass before the Sierra Madre de Chiapas mountains resume to the south, so geographically the isthmus divides North America from Central America. However, the southern edge of the North American tectonic plate lies across the Motagua Fault in Guatemala, so geologically, the division between North America and Central America (on the Caribbean Plate) is much farther south than the isthmus of Tehuantepec.