Nuevo Laredo - A United States citizen has married her Mexican fiance on a raft on the river border between their two countries, a unique ceremony designed to meet US immigration requirements.

Stephanie Guerra, 26, and Ruben Alfonso Fierro, 27, defied the swirling currents of the Rio Grande and boarded a Zodiac raft that took them from the Mexican border town of Nuevo Laredo to the US.

Guerra is a US citizen, but Fierro is not. The couple have four young children, all United States citizens. Fierro had been living for years in the US but had not legally immigrated. When he temporarily left the country, he was not allowed to return.

The fastest way for the family to reunite was to tie the knot in the United States.

Guerra and Fierro cleverly took advantage of an 1848 treaty that allows free navigation for both sides along the Rio Grande, the river that forms nearly half of the 2,000 mile long border between the US and Mexico.

On Wednesday, April 10th, Judge Hector Liendo from Laredo, Texas climbed aboard the couple's raft - in the river but technically in US territory - and conducted the ceremony that legally bound the couple until death does them apart.

US law enforcement personnel stood nearby just to make sure that none of the people aboard the raft, which included Mexican relatives, did not step off onto US soil.

While binational couples have married on bridges between the two countries for years, this is the first time that a marriage has taken place on the Rio Grande river, according to the Big River Foundation, the US-based environmentalist group that sponsored the event.

Fierro told reporters that the marriage will now make it easier for him to legally immigrate to the United States and return to his family.