Before students living in Lukeville on the Arizona border with Mexico can board a bus for school in Ajo, they must prove their Arizona residency.
Pima County Schools run the buses from Lukeville to Ajo. The Ajo Unified School District asked Pima County Schools to confirm state residency before students board buses for Ajo.
So far, 48 certificates of residency have been issued.
Certificates were not required last year, when 86 students made the nearly 40-mile daily bus trip from Lukeville to Ajo.
The state education department announced in May it was seeking $1.2 million from Ajo schools for allegedly using state funds to educate 105 students from Mexico since 2007.