If you cross the US-Mexican border at the town of Calexico you might run into a photographer named Daniel Santillan. But he's not likely to be shooting pictures of tourists. He only has eyes for Mexican schoolchildren who want an American education.
Mr. Santillan is a residency enforcer, assigned by local education officials to make sure students live in the US, not Mexico. When he's not tracking students on weekday mornings at the border crossing, he visits local homes to make sure children live where their parents say they do.
Santillan isn't thrilled about busting youngsters for living south of the border, but he accepts his job. "The bottom line is that these kids are taking up room," he says.
It's impossible to know how many Mexican students cross the border daily to attend school in the US, sent by parents who think they'll get a better education. Still, border communities have fretted over their presence for more than a decade.
Some schools are now doing more to enforce residency requirements under pressure from politicians and activists concerned about wasted taxpayer money.
Calexico's schools, however, have gone further than others by sending Santillan to photograph students at the border and requiring parents to provide proof of residency twice a year.
The school district, which serves 9,000 students in a poor southwestern California border town, wasn't overly concerned about Mexican students until about three years ago.
After all, Calexico schools didn't lose any money by accepting the students, since the state of California reimburses the district for each student it accepts. Also, Mexican students didn't necessarily stand out, since 95 percent of Calexico residents are Latino. And close relationships with Calexico's sister city in Mexico – the sprawling metropolis Mexicali – made cross-border trips easy.
District officials say they only began to take action because of complaints about overcrowding – some students had to be bused across town to schools that had room for them – and low test scores under the federal No Child Left Behind program.
"The elephant in the room is the [test-score] liability these kids bring to the table," he says.
Partly as a result of its crackdown, the Calexico district has lost 300 students and nearly $2 million in state funding that is based on the number of students in its schools. But Mr. Barraza says this has helped the overcrowded campuses.
"Enrollment was getting out of control and we had to address it," Barraza says.
Elsewhere along the border, schools pay varying levels of attention to Mexican students. In San Diego County, officials have had to tread carefully since the mid-1990s, when a video clip showing schoolchildren crossing the border in a rural area created a stir. The small school district serving the region ultimately had to expel a reported 325 of its students because they didn't live within its boundaries.
Under federal law, schools cannot ask students about their citizenship status. Even if they could ask, many Mexican children have American citizenship because they were born here. But schools can verify where students live.
The proof can come in the form of documents such as water bills or mortgage papers. In addition, the district now requires documentation if a relative who lives in the district claims to be a child's guardian and a new computer system will allow school officials to immediately identify addresses that don't exist.
"We've really tried to close a lot of the loopholes," says spokeswoman Lillian Leopold. "We think we're pretty strict, but we're not a police agency."
The district does allow Mexican students to attend its schools if they pay annual tuition of $7,435, Ms. Leopold says. No one does that at the moment, however.
Students living across the border can attend some US colleges and universities if they pay tuition. An estimated 10 percent of the students at the University of Texas-El Paso are Mexican citizens, says linguistics professor Jon Amastae, former director of the university's department of inter-American and border studies. According to news reports, some of these students cross the border to attend school.
Meanwhile, so many schoolchildren come through the El Paso border that officials created a special pedestrian lane for them. The Houston Chronicle reported that about 1,200 used the lane during a single morning in 2007.
Some El Paso residents have complained about the influx of Mexican students. But Mr. Amastae thinks most residents are on his side. "Here along the border, most people share the idea that we all have an interest in raising education levels," in both countries, he says. "Doing so benefits all of us."
• Randy Dotinga reported from San Diego and Mary Knox Merrill reported from Calexico.