Named after José María Paz, the freeway was designed by PascualPalazzo and construction was directed by José María Zaballa Carbó. It was the first freeway built in the country. The crossings with the mostimportant avenues were grade-separated; more minor cross-streets were served with traffic circles. The road had four lanes, two on each direction andlateral feeder streets of one lane on each side. The pavement was made of reinforced concrete.
The expressway at its junction with Highway 7.
Workwas started on June 8, 1937, and the freeway was opened to the public on July 5, 1941. In the 1970s the roundabout on Avenida del Libertador wasreplaced by an interchange
In 1996 the road was modernized and fully grade-separated, widening the road to three lanes on each direction and two feederstreets with two lanes each. To facilitate traffic it was decided that the colectivo bus lines travelled on these feeder roads, except the expressservice buses, which stop on these feeders. These streets have speed bumps of limit speed to 40 kilometers per hour (25 mph).