A priest in Rome is installing a large screen inside his church so parishioners can follow key moments of the trip from afar.
In Argentina, President Javier Milei has already welcomed the visit. He wrote on X that the country awaits the pope with immense joy.
The itinerary includes meetings with heads of state as well as religious events. Officials described this stretch as potentially the most politically sensitive of the journey.
When the visit was announced, it filled hearts with joy, one person told the BBC.
Leo himself disclosed the diagnosis. He later thanked well-wishers at his first public event after the operation.
Argentina’s bishops have criticised Milei’s austerity programme and sweeping cuts to social spending.
Doctors found a tumour during a routine scan last month. The growth was taken out with the lower lobe of his right lung. His medical team said the cancer had not spread. At a briefing in Rome before departure, a spokeswoman said the pope had fantastic stamina and was extremely enthusiastic about the schedule he had personally confirmed.
She said she did not think he had ever considered calling the trip off.