Salina Cruz is a major seaport on the Pacific coast of the Mexican state of Oaxaca. It is the state's third-largest city and is municipal seat of the municipality of the same name. The city had a 2005 census population of 71,314 persons, while its municipality, with an area of 113.55 km² (43.84 sq mi) had a population of 76,219, the state's fourth-largest municipality in population.

The port expanded in the late 19th century due to its location at the southern terminus of theTehuantepec National Railway, which carried freight across the Isthmus of Tehuantepec. It is situated near the mouth of the Río Tehuantepec, on the open coast of the Isthmus of Tehuantepec, and has no natural harbour. There was only a small Native American village before Salina Cruz was chosen as the Pacific terminus of the railway, whereupon a modern town was laid out and built on adjacent higher ground. The new port was opened to traffic in 1907 and in 1909 its population was largely composed of labourers. A costly artificial harbour was built by the Mexican government to accommodate the traffic of the Tehuantepec railway. It is formed by the construction of two breakwaters, the western 3,260 ft (990 m) and the eastern 1,900 ft (580 m) long, which curve toward each other at their outer extremities and leave an entrance 635 ft (194 m) wide. The enclosed space is divided into an outer and inner harbour by a double line of quays wide enough to carry six great warehouses with electric cranes on both sides and a number of railway tracks. Connected with the new port works was one of the then-largest dry docks in the world 610 ft (190 m) long and 89 ft (27 m) wide, with a depth of 28 ft (8.5 m) on its sill at low water. The works were planned to handle an immense volume of transcontinental freight, and before they were finished four steamship lines had arranged regular calls at Salina Cruz.

[The municipality

As municipal seat, Salina Cruz has governing jurisdiction over the following communities:

Agua Blanca, Boca del Río, Colonia el Bosque, Colonia el Mirador, Colonia Estibadores, Colonia Granadillo, Colonia la Brecha, Colonia Miramar, Colonia Santita, Colonia Vista Hermosa, El Ciruelo, El Puentecito, Ensenada de la Ventosa, La Brecha (Rancho Moisés Aquino), La Hacienda (Palo Grande), Las Escolleras, Palo Grande, Playa Azul, Playa Brasil (Brasilito), Salinas del Marqués, San Antonio Monterrey, and San José del Palmar