Ferrocarriles Unidos del Sureste
Ferrocarriles Unidos del Sureste was a company that operated a railroad in southeastern Mexico. In the 1930s the Mexican government decided to build a railroad into the Yucatán, connecting the national system with the isolated Ferrocarriles Unidos de Yucatán.
Source: Wikipedia — Ferrocarriles Unidos del Sureste (CC BY-SA 4.0)