But since agents from the US Border Patrol tore down the bridge at the beginning of July, the ebb and flow
that united and fed the two communities has all but stopped. Rosa Elba Madrid, a 55-year-old resident of Candelaria, whose brother lives in San Antonio, feels it as much as anyone. "I used to meet him halfway along the bridge and we would talk for hours," she says. "Now, I can't do that. It's all abandoned, all ugly."
It might be tempting
to see the bridge's removal as an isolated incident affecting two remote communities. But all along the 2,000-mile frontier there are signs - evident in migration patterns, in ageing infrastructure, in violence and in business - that a common border culture that was helping to integrate northern Mexico with the southern US is breaking apart.
One cause of this breakdown is the US administration's determination to secure its borders since the September 11 attacks and, more recently, to stem the flow
of undocumented workers from Mexico.
In recent years the US has roughly doubled the number of Border Patrol agents on its southern border and in 2006 President George W. Bush obtained
congressional approval to build a fence. Since then the administration has built more than 335 miles of barriers and plans to construct about that much again by December.
Almost everywhere along the border, there are signs of the fence going up. At Sonoyta, a small town in the state of Sonora next to Arizona, workers toil
in the hot desert sun as they drive steel posts into the ground.
Further east, by Sásabe, there is a miles-long scar where scrub and undergrowth
were cleared to make way for a metal fence about 15 feet high. It replaced a row of waist-height sticks held loosely together with barbed wire.
A second reason for the breakdown of the common border culture is drugs. Since he took office
in December 2006, Mexico's president Felipe Calderón has been fighting a bloody war with the country's powerful drug cartels.
With violence on the increase - there have been more than 2,900 drugs-related murders in Mexico so far this year, compared with 2,275 for 2007 - many US citizens who used to hop across
for the weekend have opted to stay at home.
Avenida Revolución in downtown Tijuana, which at weekends used to be full of US citizens looking for a wild time, is all but empty. Outside Pato's, a sleazy-looking
nightclub on Revolución, two men in bow ties
try without success to entice tourists to go inside. They say business is down at least 50 per cent compared with two or three years ago.
The impact of all of this on border traffic has been devastating
. According to the US Customs and Border Protection, the number of pedestrians and private vehicles crossing into the US in the South Texas region, traditionally one of the busiest, has dropped 21.6 per cent and 17.7 per cent since 1999, respectively. The fall-off has been so great that many academics have begun to ask themselves: whatever happened to Nafta, the 1994 free-trade agreement
between the US, Canada and Mexico?
It is against this backdrop of more restricted borders, drugs-related violence and dying border tourism that companies in the region are trying to operate. Both US and Mexican businesses with cross-border trade complain about worsening bottlenecks
to enter the US.
Gustavo del Castillo, a Mexican academic at the College of the Northern Frontier in Baja California, argues that many of these delays are caused by the absence of infrastructure investment, particularly on the US side. "Unfortunately, commerce is not a priority for the US," he concludes.
Clinton Roberts, a Texan construction worker from Marathon, 70 miles from the border, is in no doubt about what all of this means. "We shared a border culture with the Mexicans that I, as a Texan, was proud to be a part of," he says. "Now that culture is being destroyed."