Argentina – Chile

The boundary, which begins in the west at the Caspian Sea and generally runs in a west-east direction to the tripoint with China, is exceedingly complicated in some locations. Although rivers like the Maly Uzen, Ural, and Uy are used in some places, the border is largely made up of overland boundaries that cross the Eurasian Steppe. The border crosses Botkul Lake. The border passes via the Altai Mountains in the far eastern region.

In the dry Puna de Atacama plateau, the northern end of the boundary creates a tripoint with those at the borders with Bolivia and Chile. The border stretches southward till it touches the water where the Atlantic Ocean and Strait of Magellan converge. The Isla Grande de Tierra del Fuego's southern boundary follows a meridian that divides the island in half. A few kilometers southwest of Ushuaia, in Beagle Channel, this boundary meets the ocean.

The Treaty of Peace and Friendship of 1984 between Chile and Argentina, an everlasting treaty, was signed at the Vatican by officials of both countries. It came about in November 1984 following protracted talks and mediation by John Paul II. An agreement between Argentina and Chile to define the border line between Mount Fitz Roy and Mount Daudet and put an end to the long-standing dispute was signed on December 16th, 1998. The border between Mount Fitz Roy and Mount Murallón, however, is still up in the air because the two nations couldn't agree on it.

Length: 5,300 kilometers