The US is building a concrete wall to stop immigrants crossing the border
Jim is sitting in the United States, staring at Mexico.
In the distance, the moon glistens on the waters of the Rio Grande, the winding river which separates the two countries.
Its light isn't needed tonight. Jim, who doesn't want to give his surname, can see in the dark thanks to a thermal imaging camera.
"It shows up body heat," he explained. "If there's a human being out there, they'll appear white."
The gadget is part of an array of tools used by the Texas Minutemen.
They are a self-styled group of American patriots who patrol the border at night, looking for illegal immigrants.
"They'll walk from the river into town where they can vanish," said Jim.
The Texas Minutemen 'spot' illegal immigrants for border patrols
"I've seen as many as 10 crossing here at one time."
The Minutemen don't capture suspects themselves.
They work as unofficial spotters, calling the government's own border patrol if they see something suspicious.
They also don't get paid. The organisation is funded by donations.
"The majority of us here are veterans. You feel a certain pride for your country," said Joe McLellan, the Minutemen's co-ordinator for the town of Mission, Texas.
"It's the people coming across. The drugs, the poison for our children."
Asked if the Minutemen are racist, Joe replied: "We're not racist. When we see people in the dark coming across the river, we don't know what nationality they are."
The scale of the problem faced by the United States is huge.
Recent estimates put the number of people living in the country illegally at around 12 million.
Despite having no legal status, many receive some form of publicly funded benefits, including emergency healthcare.
The Rio Grande river separates Mexico from the state of Texas
Undocumented immigrants were estimated to have cost Texas hospitals $1.3 billion (£752m) in 2006.
Cross-border drug smuggling is also a growing problem, with the US Drug Enforcement Agency reporting record seizures in recent years.
These factors have led the United States to take a harder line.
The government is building a concrete wall along the border with Mexico.
The barricade will stretch from Texas to California. However, it will not cover the whole country.
"That's a waste of taxpayer's money. Who is to say they can't go around the wall?" said Gloria Garsa of Granjeno, Texas.
A section of the wall is due to be constructed less than a mile from her home.
She added: "It all started with terrorism. The terrorists started coming into New York through Canada. Where is their wall?"
Some anti-immigration groups claim scepticism about the wall in border areas comes from the largely Hispanic population in the south having a vested interest in keeping the borders open.
Attitudes tend to harden farther north.
In the town of San Antonio, 200 miles away, Joseph Colon is packing up after spending the day tiling a floor with his brother-in-law.
He said: "They're just taking over everything and leaving us with nothing.
The Texas Minutemen use thermal imaging cameras at night
"I've been looking for work for six months but the illegals are just taking everything. If I work, I will pay my taxes."
Disgruntled voters looking for a solution during the current election campaign may be disappointed.
There has been relatively little debate about the issue of immigration.
It's partly because the economy has pushed it off the 'hot topic' list and partly because there is little difference between the candidates to debate.
Both Barack Obama and John McCain have supported programmes, now or in the past, to help illegal immigrants gain citizenship providing they pay back-taxes and learn English.
Republican John McCain, in particular, has come under attack for his views on immigration.
Conservatives within his own party disapprove of what they see as an amnesty for illegals.
Meanwhile, both men are remaining careful not to scare off Hispanic voters.
Taxi driver Anthony Carreon says in these tough financial times the country may even need things to remain the way they are.
"The illegals are doing the jobs that the Americans don't want to do.
"People here pay them pennies for the type of work they do. Hard work. Americans are not going to do that."
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