About 345,000 buses crossed into the United States in 2009 of the nearly 107 million total vehicles coming from Canada and Mexico, federal transportation statistics show. But how many were school buses?

That answer remains unanswered. The U.S. Department of Transportation's Bureau of Transportation Statistics (BTS) released its sixth-consecutive year of research compiled with the help of Canadian and Mexican authorities. The study found that merchandise trade has increased by $24 billion since 2004. But the survey doesn't break down the category "bus" and does not track the most precious cargo, school children.

There are literally hundreds of American school districts situated along both borders, but, according to a few school districts spoken to for this article, these days there are few trips out of the country, especially to and from Mexico. Canada is another story.

School transportation operation in the United States and Canada are similar, and there can be regular activity trips if few rare instances of regular routes crossing the border. But many retired American school buses make their way south of the border into Mexico and Central and South America especially for transit from town to town, as STN "Routes Around the World" blogger Anson Stewart has discovered.

Reports from school districts located along the U.S.-Mexico border indicate that any route or activity trips across has been rolled back considerably due to new requirements for all visitors to Mexico to have valid passports, as well as increased drug cartel violence.

The May 2009 edition of School Transportation News magazine contained a story of security concerns along the U.S.-Mexico border. Hundreds of students who attend Deming Public Schools and other districts in southern New Mexico are bused across the border each day to attend class. Those children were born in the United States, have dual citizenship and live in Mexico with their families. But elsewhere, districts are refusing to send their buses out of the country.

A representative of San Ysidro School District south of San Diego and across the border from Tijuana, said absolutely no school trips via bus or any other vehicles are taken into Mexico. The transportation department verifies student addresses when applications for transportation services are submitted. In addition, proof of residency such as a rental agreement, mortgage and utility bills are reviewed, a requirement placed on all schools in San Diego County. San Ysidro also bans activity trips into Mexico because passports and parental permission would be required.

Then there are economic hardships. A year and a half ago, the economy forced San Ysidro School District to cut a large portion of its regular routes as well as rider eligibility for its students with U.S. citizenship. School bus service is now only available to pre-kindergarten through third-grade students and per IEP guidelines. Some students through eighth grade who live in certain communities also remain eligible for the school bus.

At El Paso ISD in Texas, school buses either on regular route or activity trip service also do not travel into Mexico, not only because of passport requirements but also because of increased violence between Mexican law enforcement and the cartels. A spokesperson said U.S. citizenship is also required of all student riders.

San Felipe Del Rio ISD, situated on the Rio Grande across from Cuidad Acuna, Mexico, and about 150 miles west of San Antonio, has not transported children from over the border for at least the past decade. A school spokesperson said the district performs no trips to or from Mexico, whether regular route or field trip. The transportation department refers to a central list of eligible riders and only transports those students to and from their U.S. residences. The spokesperson added there have been incidents in the past when students were smuggled over the border and dropped off at established bus stops. But all drivers now check each student boarding against the rider eligibility report and refuse access to any child not listed.

What about the border with Canada? The Blaine School District in Washington State must send a school bus across the border a few times a day to pick up and drop off about 50 students who live on Point Roberts, which is situated on the southern tip of a peninsula that begins in Canada and dips below the 49th parallel. Twice as many students were transported to and from Point Roberts a few years ago before budget cuts, said Carl Wagelie, the transportation director at Blaine

The unusual route takes the school bus up Highway 99 and into White Rock, British Columbia. From there, the bus must travel about 30 minutes to its destination but never is parked in the country, eliminating the need for border agents to board the bus with drug-sniffing dogs and to check student passports. However, that's the process Blaine buses and those from other districts must go through when traveling into Canada on field trips, and for Canadian school bus drivers to enter into the United States.

Wagelie added that all students on the regular route to and from Point Roberts have proof of citizenship on file at the administration offices, and the bus driver brings a notebook containing similar information just in case.