The Posadas line reached Paso de los Libres in 1894 and was extended to Santo Tomé in 1901.

Once the section from Santo Tomé to Posadas was opened some years later in 1911 an international rail connection with Paraguay was established.

[3] In 1907 the ANER took over British-owned East Argentine Railway, which operated a line from Monte Caseros south to Concordia in Entre Ríos Province.

Two years later a branch line from San Diego to the port of Goya on the River Paraná was completed and in 1915 the line from Concordia was extended south to the river port of Concepción del Uruguay.

[4] Later that same year the ANER established a joint administration with the neighboring British-owned Entre Ríos Railway.