The Catholic hierarchy in the U.S. is promoting Our Lady of Guadalupe, and she has become an image for the pro-life movement as well as for women's issues, the priest noted. Other ethnic groups are growing in devotion to her, including the Indian and Polish communities.
Sometimes the mortifications of the pilgrims are extreme. In severe cold weather, senior citizens will still walk through the snow.
"Here we don't judge them. We just get them to Our Lady," Sanchez said. "Our job is to make sure you get there safely."
Sometimes safety is a concern.
Once, a group of pilgrims traveled on foot through the northern Illinois city of Rockford on their way to the shrine. They were holding a banner and singing songs. A group of people voicing anti-immigrant attitudes began to assault them, told them to get out of the neighborhood, and threw rocks at them.
"It's not necessarily a wonderful experience," Sanchez said. "They continued their pilgrimage and made it."
The priest suggested the pressures of contemporary American culture also drive devotion.
"Whatever the country is feeling, the community is looking for hope," he said. "We live in a time when people feel less welcomed, where people feel scared, and often the only thing they feel they can trust is their prayer, and the one thing that has got them through the hardest times of their lives thus far: Our Lady of Guadalupe."
The feast day can create a major traffic issue, with 300,000 people in a 36-hour period. Planning begins months in advance, with the local police department helping to manage the situation.
There are 150 to 200 volunteers just to care for the pilgrims Dec. 11-12.
"Our job is to take care of the pilgrims when they come. They are trying to get to her," Sanchez said, adding that they aim to help the pilgrims feel loved and well-fed.
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"We make sure that the people's experience is one that is very, very festive," he said. "There's a lot of music, a lot of serenading mananitas, a lot of indigenous dancing, what you see in other shrines."
Sanchez said there is a strong custom in Mexican Hispanic culture of "mandas," which means "promises" in English.
"People make promises to Our Lady of Guadalupe for a specific intentions or miracles or an act of gratitude," he said.
"The problem is a lot of people here in the U.S. can't go back to Mexico. There are immigration issues, economic issues, health issues, there are a lot of issues that keep them from going to Mexico City to fulfill their life's promise to Our Lady."
To help these pilgrims fulfill their promises, the Basilica of Our Lady of Guadalupe in Mexico City has offered them the same graces and indulgences if they visit the Illinois shrine.
Other pilgrimages come during the novena, the nine days before the feast day.