The Libertador General San Martín Bridge () is a cantilever road bridge that crosses the Uruguay River and joins Argentina and Uruguay. It runs between Puerto Unzué, near Gualeguaychú, Entre Ríos Province, Argentina, and Fray Bentos, Río Negro Department, Uruguay, 100 km upstream from the start of the Río de la Plata, and 320 km the Atlantic Ocean.
The bridge has a total length of ( in Argentine jurisdiction and in Uruguayan territory), including the bridge and accesses embankments.
Studies for the construction of a bridge over the Uruguay River were started in 1960 by a joint commission, which decided that the best place for it would be between Puerto Unzué and Fray Bentos. In 1967 the two countries signed an agreement ratifying the location, and in 1972 the construction contract was awarded to the International Bridge Consortium (Consorcio Puente Internacional), setting the cost at $ 21.7 million, then adjusted upwards.
The bridge is named after José de San Martín, a major figure in the struggle for independence in Argentina, Chile and Peru. It was officially inaugurated on September 16, 1976. It was opened for public use and the next day it started functioning under a toll regime. There are other bridges upstream, but no further bridges downstream.
See also General Artigas Bridge Salto Grande Bridge Cellulose plant conflict between Argentina and Uruguay List of international bridges
References
Puentes sobre el Río Uruguay (in Spanish)