After the change of route of National Route 9, in the late 1950s, the section from Avenida General Paz and Campana was changed to RN12. In 2005 the 8 km section between National Route 9 in Campana and the Bartolomé Mitre bridge access over the Paraná de las Palmas river changed to Buenos Aires provincial jurisdiction as a new section of Provincial Route 6. RN12 runs over the ol roadbed of National Route 193 to the bridge over National Route 9 in Zárate.