Before I left the center ring of the Ringling Bros. and Barnum & Bailey Circus’s Blue Unit traveling troupe, Father Frank Cancro handed me a postcard. On the front was Mary, her arms outstretched, with a multicolored shawl draping down from her hands like a circus tent. A lion, a tiger and a dancing dog were at her feet, with a clown, an acrobat, a juggler and others contained within the safety of her tent. They all stood on a star, at the center of the center ring.

“Mary, Mother of all who travel down the road, pray for us!” the back of the postcard read.

Mary, Cancro explained, protects those who spend their lives in the circus. That includes Cancro, who has a parish in North Carolina but also works as a “circus priest,” spending three to four days every month with circus folk. His off-white vestments are embroidered with a small, sparkling elephant.

Cancro was in the center ring at the Patriot Center in Fairfax, Va., with Father Jerry Hogan, a Boston-based priest who runs the circus and traveling show ministry in the United States. Hogan is the circus chaplain, a role he’s held for 22 years.

They were there to perform sacraments for the Ringling group: baptisms, confirmations, first Communions. Those participating were trained by a nun, Sister Dorothy Fabritze, who travels with the circus along with Sister Mary Seibert for a few months every year, before moving on to another circus.

What the nuns and the priests do is a continuation of a relationship between the circus and the church that began 90 years ago, when a young, bespectacled priest named Monsignor Elslander began to bless the Ringling trains as they left Sarasota, Fla., every spring.

“There’s been a Catholic presence on the Ringling Brothers since roughly 1928, when the Ringling Brothers moved to Sarasota,” Hogan told me. “There was a pastor there who’d just started at St. Martha’s Church.” That pastor, Elslander, stayed for decades.

Then, as now, circus people came from all over, including many South American and European countries with large Catholic populations. Soon, Elslander was doing more than just blessing trains and waiting for the circus to return to its winter base of operations. Catholics need a pastor, they need sacraments, they need Mass; Elslander could do that for the traveling Catholics employed by the circus.

Ever seen “The Greatest Show on Earth,” the 1952 film, Hogan asks. (I haven’t.)

There’s a priest who blesses the trains in that film as well, Hogan says. He was based on Elslander.

And Ringling was doing more for the church, too: When Elslander’s small Sarasota parish outgrew its sanctuary, Ringling held two yearly shows at St. Martha’s property from 1935 to 1941 to help raise funds for a new place. Those benefit shows, smack in the middle of the Great Depression, funded the new church in less than a decade.

The famous Wallenda family performed at the church benefit in 1938, Sarasota Magazine notes.

St. Martha’s is still known as the “Circus Church,” although the Catholic priests and nuns who work in circus ministry now report to the U.S. Conference of Catholic Bishops, the Washington-based governing body of the Catholic hierarchy in America. After Elslander came Pastor Ed Sullivan, Hogan said.

Hogan himself caught the circus bug early, he told me, from a childhood neighbor who worked for Ringling.

Hogan has been through a lot with the Blue Unit. He was there in 1994 when the unit’s train, touring its Romeo and Juliet act, derailed on a foggy morning in Lakeland, Fla. Two performers were killed, and Hogan was flown in to help comfort their friends and families.

Ramon Garcia, the Blue Unit general manager whose three children all participated in the April Mass in the center ring, was close to one of the performers who died in that crash. “Back in the day, you know, Father Jerry was a very instrumentive person to walk us through the ropes and make us believe we were safe,” Garcia said.

Last spring, when the rig for the unit’s “human chandelier” act collapsed in Providence — severely injuring the eight performers who fell, suspended by their hair, 20 feet to the ground — Hogan was with the unit within the hour.

Other circuses have built their own relationships with the church over the years, too.

Sister Dorothy has been coming to Kelly Miller Circus for only a few years. The “mud show” circus, which moves daily, tent and trailers in tow, might be new to the nun, but it is not new to the church: Before Fabritze, there were Sister Priscilla Buhlman and Sister Joel Byrne of the Little Sisters of Jesus. Kelly Miller gets regular clergy visits, too, usually from Father Dick Notter, the third of the church’s trio of circus priests.

John Ringling North — son of the sister of the famous Ringling Bros. — bought Kelly Miller in 2007. North, a wiry man in a white cowboy hat who isn’t afraid to cuss a little in front of Fabritze, sits ringside for every performance. He knows how far back the circus and the church go: As a child, he recalls, he’d watch Monsignor Elslander bless the Ringling trains as they left Sarasota every spring.

Like North, Cancro has a long circus history, too: Forty-five years ago, before he even attended seminary, Cancro went to the Ringling brothers’ clown school.

“My priesthood,” he said, “went on without any real connection to circus” — until one day in 2010, when Fabritze showed up at his office and saw a photograph of a clown on his wall.

“She wanted to know who it was, and I said it was me,” Cancro said. “And then I had to tell her my background.”

He sighed. “Next thing I know, I have a call from the Bishop’s Conference to show up at this meeting the following January to become part of the circus and traveling people’s ministry.”