So some have tried to defend the border with their own arms, and it could land them in prison.
CBS News Correspondent Bob McNamara reports from the frontlines of the United States' losing battle against illegal immigration.
"These people sit on the hill, and they watch you," Pat Bordelon says. "They'll wait until you're gone, and they're sure you're not here, and they'll come and rob you."
Bordelon says living on the Rio Grand is life on a border battleground.
"We're scared. My house....I got it up for sale now because we can't live here no more," Bordelon says.
The daily invasion of illegal aliens from Mexico has gotten personal, Bordelon says.
"I had one guy (who) even told me his name," Bordelon says. "And he said, 'I come to kill you, gringo.' What am I supposed to do? This guy out in the river coming across the river....What am I supposed to do? I'm not going to tell you what I did. But what am I supposed to do?"
From his riverfront home, Bordelon has been linked to two shooting incidents in the last eights months: the wounding of one as well as the suspected killing of a 16-year-old. The Mexican boy was shot as he fled across the river after trying to break into Bordelon's house.
"I didn't do what they claim I did," Bordelon says. "They claim I shot someone. I did not."
The dead boy's brother admits the burglary attempt. But his heartsick mother wants Bordelon indicted by a Texas grand jury, now investigating the killing.
Paul Berg of the U.S. Border Patrol acknowleges the dangers. "I wouldn't live there," he says. "Simply because of the traffic that's coming through there day
On night-vision cameras, Border Patrol agents have seen the illegal invasion here take on the tactics and size of an advancing army.
Arrests last month in the Del Rio area alone totaled more than 20,000 illegal immigrants. And some here are tempted to take the law into their own hands.
"If my family or my property is threatened, I wouldn't hesitate one bit," says David Rosser, Bordelon's neighbor.
Bordelon goes on trial soon for wounding a young Mexican man in the back as he stood in the river last summer. But hundreds here signed petitions saying Bordelon was defending his property.
"No one wants to kill anyone," says Tommy Vick, Bordelon's neighbor. "We would a whole lot rather they just leave us alone; that's all they have to do - just don't come over here, try to take our belongings. It's real simple."
But solutions are not simple at all here, a land where the line between right and wrong can often be as murky as the Rio Grande River.
Read a recent commentary on illegal Mexican immigration by Dan Rather:Disorder South Of The Border.