Retablo of Jose Cruz Soria, 1960.

The paintings in “Miracles on the Border: Retablos of Mexican Migrants to the United States,” on view at the Princeton University Art Museum through July 7, have instant appeal. Smallish in size (each is about the size of a notebook), they are brightly colored, often with a heavenly figure in a blue robe, and contain endearing characters and their stories of miracles. Viewed together, they form a kind of picture book for adult readers; what a graphic novel might be if everyone got to contribute a page.

But beyond their beauty and charm, these retablos help us understand who the people are who are crossing the border. Despite what a certain administration would like us to believe, the works in this exhibition show ordinary people who love and want to take care of their families, and who may have experienced a series of misfortunes from which they escaped and want to pay thanks.

“Miracles on the Border,” offered in both English and Spanish, is the art museum’s first bilingual exhibit and is part of the “Global Migration” seminar that looks at significant issues surrounding transnational migration. “This feeds into the campus dialogue about migration and crossing borders,” says Juliana Ochs Dweck, the museum’s curator of academic engagement, whose role is to make the collections accessible and relevant.

In Mexico retablos are placed as votive offerings in home altars, shrines, or churches in gratitude for divine protection and meant for public viewing. They are usually produced by anonymous artists but signed and dated by the supplicant. Tin remains the traditional means of support for the retablos, although wood, cardboard, and plastic substrates have been used. Even license plates, condensed milk cans, and other scrap materials have served as support, according to Dweck. Oil paint is traditional, but other practitioners use whatever is available — acrylic, gouache, even house paint. Their use of color and composition influenced 20th-century artists.

“An individual who had experienced disaster or tragedy and recovered would want to have a retablo made to fulfill a vow to a holy figure,” says Dweck. “They would go to an artist with expertise in retablos and describe their experience, be it healing or thanksgiving or gratitude for the return of a son from America or prison or surgery. The artist would illustrate the scene and describe it in words, and the individual would pay for the work.”

Some artists do sign their names and include phone numbers and addresses to drum up business, but not in these. The artists were usually untrained — occasionally a supplicant would paint his or her own. “Even though they are religious objects, they are expressions of indigenous identity,” says Dweck.

Retablos have their roots in the Catholic churches of medieval and early modern Spain from the 12th century on. The faithful prayed to these altar sculptures or paintings of saints for intercession: healing, protection from danger, influence over the course of events. These were replicated on a smaller scale in Mexican churches, and of two types: Santos, images of saints, which were reproduced for home devotion; and ex-votos, made in gratitude for a saint’s protection and donated to the church.

The Virgin of San Juan de los Lagos is a distinctly Mexican manifestation of the Virgin Mary, invariably clad in a blue robe. She is frequently called upon for help by Mexican migrants to the U.S.

The retablos on view here were collected by Douglas S. Massey, a professor of sociology and public affairs at Princeton University, and Jorge Durand, a professor of anthropology at the University of Guadalajara, Mexico. Massey and Durand are co-directors of the Mexican Migration Project, sponsored by Princeton University and the University of Guadalajara. Created in 1982, the Mexican Migration Project collects data to track patterns on the characteristics and behavior of documented and undocumented Mexican migrants to the United States and records how they change over time.

“These retablos are the more ethnographic side of our studies,” says Durand during a slide lecture in conjunction with the exhibition.

“We wanted to tell the story from the migrant’s point of view, and this was a good way,” says Massey during the same presentation.

A photo in the exhibit shows how these retablos would be hung in a church, strung from pegs on a wall, fitting as many as possible, with rosary beads and jewels sandwiched in between. So densely hung are these gestures of gratitude that, over time, older retablos are removed to make way for newer ones. It should be noted that those in the Massey-Durand collection were purchased from galleries and antiques dealers. Many still have their strings intact, and some have their edges taped.

“How they ended up in the galleries and antique stores we don’t really know,” says Dweck. “Each has its own trajectory. Some churches store and archive them, some sell them, and others leave them for the taking. These collectors were looking for a very specific kind of narrative.”

Although each story ends with a tale of divine intervention, these retablos catalog the travails of migration. It is generally when one has explored every human possibility, to no avail, that they seek intercession from otherworldly spirits.

In one, a grandmother gives thanks to the Virgin for restoring health to her grandson. We see a boy in a hospital bed while a man in a suit watches over him. Suspended over an ethereal levitated female figure are two cherubs with wings. A black-and-white photo booth-type shot of the grandson has been nailed onto the painting. (Several retablos by this same artist incorporate photos, a signature technique.)

In folk art tradition, the style is flat painting, without much use of shading or contour. Some scenes include buildings, trains, trucks, and mountains. Christ on the cross is a frequent motif. Hospital beds with figures tucked under white sheets are a common theme, as those giving thanks called upon the divine to help heal sick relatives. Others pray for their children who have gone abroad, for illumination of the road (both literal and figurative).

There are miracles here for sure — a woman walking alongside a track with a little boy she holds by the hand crosses a bridge, and the two are overtaken by men in a vehicle. She invokes the holiest virgin and they suffer nothing more than a few blows.

Another falls from a handcar in Florence, Kansas, and was saved by the Miraculous Lady of San Juan. The Virgin saves men who are mistaken for bandits; those for whom medical professionals have given up hope; safe return from war; suffering from “bad cramps”; those who are financially in debt; those seeking work or securing checks owed by the insurance company; or suffering from hepatitis or cancer. She enables many to attain freedom.

The retablos can be divided into sections, according to Massey: making the trip, difficulty in finding work or finding one’s way, the danger of falling sick in a foreign land, getting by in the U.S., and the joy and relief of returning home.

“These are just regular people making a difficult journey to make money to take care of their families,” says Massey. “They endure incredible risks and are grateful to have the chance to go home.” He posits that if immigration were legal and the borders were open, many would go home to their families.

We learn that Mexican citizens can be drafted in the U.S. Army — there are retablos giving thanks for getting them out of the Vietnam War.

“The men usually ask for a favor for themselves,” says Durand during his talk. “Women ask for something for a son or a husband.”

“The women are especially vulnerable when they cross the border,” says Massey. Because of fortifications in San Diego and El Paso, people are crossing the Sonoran Desert into Arizona, enduring especially harsh conditions.

The exhibit concludes with the influence of retablos on modern art. Frida Kahlo famously used the retablo’s votive features and compositional strategies in her work, such as in “Henry Ford Hospital,” her autobiographical work in which she is giving birth to a stillborn child. Her unclothed figure lies in a pool of blood on the white sheets of a hospital bed — the corset she wore to help with a spinal injury lies nearby, on the floor — while an enlarged fetus entangled in an umbilical cord floats above (the painting is referenced but is not in this exhibit).

Kahlo’s husband, Diego Rivera, called retablos the “one true and present pictorial expression of the Mexican people.” (Kahlo and Rivera’s personal collection of retablos is currently on view in a replica of the Mexican museum Casa Azul at the Brooklyn Museum through May 12.)

Nahum Zenil, a contemporary Mexican artist, paints his own self-portrait sealed in a decorative shrine surrounded by flames, roses, and the little paper cupcake holders in which votive candles come. Rather than beseeching the heavens for redemption, his image confronts the viewer with a serious but impassive expression. An openly gay artist, Zenil underscores the church’s power to shape national identity. “Rather than entreating a holy figure he’s confronting the viewer, becoming the holy figure,” says Dweck. “It’s almost a shrine itself, an image of human suffering — engulfed in flames — and shows the power of the church to change his identity.”

So, then, for those of us who don’t believe in divine intervention, could these retablos have a kind of placebo effect, that is, could a believer have miracles alter their lives just by the very act of believing?

“I’m not Catholic so I can’t speak to the experience,” says Dweck. “These are expressions of gratitude more than a request: if I survive a tragedy I will make an offering. Having survived, they are fulfilling their end of bargain. Through retablos they gain an agency to create change.”

“Although created by humble hands, the imagination and details on these small works pay homage to not only the personal miracles but are a showcase for others,” says Massey. “They are transnational objects that become a testimony to a people who might otherwise be erased.”

Miracles on the Border: Retablos of Mexican Migrants to the United States, Princeton University Art Museum. On view through July 7. Free. Tuesday, Wednesday, Friday, Saturday, and Sunday, 10 a.m. to 5 p.m.; Thursdays, 10 a.m. to 10 p.m. Closed Mondays. 609-258-3788 or