The video shows the young girl clinging to the smuggler's back as he climbs down the U.S.-Mexico border wall with a rope onto the California side.
He is seen walking with the girl for a short time before he leaves her and returns to climb back over the fence alone.
Border Patrol agents spotted the smuggler climbing down the wall on video surveillance but opted not to approach because of the risk to the girl.
The child is from El Salvador. She was examined for a welfare check and then brought to the El Centro Sector Processing Center for a medical evaluation and processing.
The incident happened Tuesday morning about two miles west of the Calexico Port of Entry.
"No one, let alone a child of any age or race, should be exposed to the multitude of dangers when crossing illegally into this country," said Chief Patrol Agent Gregory K. Bovino. "Smugglers will always view children as a commodity to gain a profit, disregarding the safety and well-being of any individual except their own."
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