Atlanta, GA - Dallas, TX - San Antonio, TX - Monterrey, Mexico - Mexico City, Mexico - Guatemala City, Guatemala - San Salvador, El Salvador - Managua, Guatemala - San Jose, Costa Rica - Panama City, Panama - Medellin, Colombia - Quito, Ecuador - Lima, Peru - Nazca, Peru - Cuzco, Peru - Puno, Peru - La Paz, Bolivia - Santa Cruz, Bolivia - Puerto Suarez, Bolivia - Corumba, Brazil - Campo Grande, Brazil - Sao Paulo, Brazil - Rio de Janeiro, Brazil.
It is the best route. It is possible, since I have seen many American cars around where I live (Curitiba, Brazil).