BUENOS AIRES — It was a sweltering afternoon at the rundown central bus station in Argentina’s capital, but Amelia Cartes Novoa was beaming despite the intolerable heat.

“I’m so excited,” Ms. Cartes said as she waited on a platform for the bus that would take her on a 21-hour ride across the Andes. She was on her way to attend a Mass that Pope Francis will celebrate in Santiago, Chile’s capital, on Tuesday.

“I’ve done this trip many times before but this one is particularly special,” she said.

Ms. Cartes is among the tens of thousands of Argentines planning to make a pilgrimage to Chile during the peak of the summertime holiday to catch a glimpse of the pope, who was born here in Buenos Aires. Much to the chagrin of many of his countrymen, Francis has not set foot in his homeland since his election in March 2013.

In contrast, Pope John Paul II visited his native Poland in 1979, less than a year after he became pontiff. His successor, Pope Benedict XVI, went to his homeland, Germany, during his first foreign trip in 2005.