Perhaps the most (in)famous roads in Argentina is the Ruta 40, running all the way across the country North-South. It stretches some 5224km from the Southern tip near Rio Gallegos to La Quiaca at the Bolivian border in the North. It crosses 11 provinces and 20 National Parks. It begins at sea level and reaches almost 5000m in the Salta region. Very few countries in the world can boast such a long road across so many different regions!
Certainly its longest road, the Ruta 40 is an icon in Argentina similar to the Route 66 in the United States. Many books have been written on the Ruta 40, and travelling the entire length is an epic journey, especially in the South where it remains an untamed, wild and remote undertaking. More details can be found on the (Spanish) Wikipedia page.
On my journey up from Patagonia to Bolivia I happened to ride on the Ruta 40 several times. Probably less than 10% of that distance was on gravel roads, so my experience was perhaps a tamed one. That said, there have been some slow sections on the infamous “ripio”, with dust, sand, washboard, wind, heat, lack of water, and steep hills reducing the cyclist’s speed often to walking pace. Below are some photos of those sections between Mendoza and Salta.
As far as I know there is not a single, designated road called the “Panamerican Highway” across the entire length from Alaska to Patagonia. But I’m sure that every cyclist undertaking this journey of the Americas will travel some section on the iconic Ruta 40 in Argentina.