The Isthmus of Tehuantepec, located in the Mexican states of Veracruz and Oaxaca, is the narrowest part of Mexico. It is also the narrowest land area located between the Gulf of Mexico (on its north) and the Pacific Ocean (on its south).

At its narrowest point, the isthmus is 125 miles long.
The Mexican government is currently involved in a major project to increase the use of the Isthmus of Tehuantepec for the shipment of cargo.
It’s called the Corredor Interoceánico del Istmo de Tehuantepec (CIIT), the Interoceanic Corridor of the Isthmus of Tehuantepec. It’s under the authority of the Mexican Navy.
There’s already a railway across the isthmus, which has been there for over a century. As part of the project, the railway is being modernized. The project also includes highways and industrial parks along the railway.
The seaports of Coatzacoalcos (on the Gulf of Mexico) and Salina Cruz (on the Pacific) are being modernized and expanded.
The goal is to move containers overland from port to port, across the isthmus, in under six hours.

The CIIT is being promoted as a rival to the Panama Canal and it’s supposed to be completed by June of this year, 2026.