I join a few dozen people on a chilly Saturday trudging along a muddy horse trail on the southernmost tip of California: San Diego County.

We head toward the shores of Imperial Beach, where the immense border wall that bisects the United States and Mexico snakes across the outskirts of Tijuana and disappears into the Pacific Ocean.

After about 20 minutes, the sticky mud gives way to wet sand. Bundled in heavy winter coats and hats, the procession marches along the beach for another mile.

The border wall and Tijuana’s imposing Monumental Plaza de Torros bullring gradually come into view through a veil of sea mist.

“For 21 years San Diegans and Tijuanans have been coming together along this border to celebrate Christmas,” says Christian Ramirez of the American Friends Service Committee, an advocacy group that helps organize the annual La Posada Sin Fronteras.

For this event, border agents allow people to access a secured area on the U.S. side, and visit with people on the Tijuana side through small gaps in the border fence.

“Today we stand here not being able to touch one other, not being able to pass food across the border,” says Ramirez.

“Despite that division, folks continue to come here and celebrate this very beautiful moment for us.”

Carlos Aragon-Padilla traveled here from South San Francisco to see his sister, nephew and other relatives. He has not seen them since last visiting Mexico about 10 years ago. The family drove 24 hours from Mazatlan -- nearly 1,000 miles -- to attend the posada and see Carlos.

Though separated by the border fence, the family presses up against the fence and spend the entire afternoon together talking, laughing and shedding more than a few tears.

“They are my whole life, the loves of my life. My siblings, my nieces and nephews, my sister’s grandchildren,” says Aragon-Padilla.

“They are the ones who push me the most, to make it in this country. To really try my best.” Aragon-Padilla won asylum in the U.S. after coming here without papers about 20 years ago.

One of those relatives is 5-year-old Jesus, a nephew that Aragon-Padilla is meeting for the first time. The boy sings a classic Mexican ballad, “Mexico Lindo y Querido,”  for his uncle. It’s a song that expresses Aragon-Padilla’s own longing to someday return, even in death, to his native land -- his Mexico lindo, or beautiful Mexico:

'My beautiful and beloved Mexico should I die far from you let them say I'm asleep and bring me back to you

Let them say I'm asleep and bring me back to you my beautiful and beloved Mexico should I die far from you'

-- Chucho Monge

There will be no cross-border family reunion today for Yolanda Varona.

She's lived in Tijuana since being denied re-entrance to the U.S. several years ago after having a tourist visa revoked.

Varona is attending the posada with a group of other women who have all left children or grandchildren behind in the U.S. after being deported or otherwise losing their legal status. But Varona did get to see her adult son, who’s now a U.S. citizen, at a border event here earlier this year.

“One of my grandchildren came, too, but I didn't like it. She thinks I’m in jail.” says Varona.

“She is too little to understand. She doesn't know I'm deported. I don’t want to see her come back here (to the border). She just couldn't handle what she saw.”

Varona says it was still important for her to attend today’s posada.

“This event, especially, for me signifies our desire that they remove this fence,” says Varona.

“To let us return to the U.S. We are asking to be back in our homes.”

There are also a few non-Latinos celebrating the posada on the Tijuana side, including a grizzled Irishman with Santa Claus white whiskers.

“Patrick Murphy, very Irish,” laughs the Rev. Patrick Murphy.

“We do posadas every night, though we don’t do it as elaborately as today.”

Murphy runs Casa del Migrante, a Roman Catholic aid group in Tijuana that provides shelter and other help to immigrants recently deported from the U.S.

He says the theme of the traditional posada story, of Joseph and Mary repeatedly being denied shelter and eventually finding it, takes on added meaning at La Posada Sin Fronteras.

“It is a symbolic reminder for us to come together in prayer, to remind people that there are a lot of people that need posadas,” says Murphy.

There is a political subtext to the border posada. But the political sloganeering is kept to a minimum, replaced instead by traditional Christmas carols sung in Spanish and English and numerous speakers touching on the themes of shelter, family and welcoming the stranger.

“For this little moment the great tension and many opinions that the immigration debate raises, all of that disappears,” says Christian Ramirez of the American Friends Service Committee.

“And I can’t help but to have my heart warmed in what is perhaps one of the coldest places in our country: the U.S.-Mexico border.”

As sunset approaches, celebrants brace themselves against the chilly ocean winds. Those on the U.S. side prepare to leave.

U.S. Border agents need to clear the area.

People pull themselves from the border fence, and say goodbye to friends and relatives on the other side of the border they may not see again until next Christmas.