WASHINGTON — An Associated Press analysis of Border Patrol records finds that agents have racked up daily overtime at a cost of about $1.4 billion in the past six years while the number of arrests of illegal border crossers has fallen to the lowest level in nearly 40 years.

In practical terms, agents average two hours a day in overtime.

Over the course of a year an agent can earn about $15,000 more than the base salary. Agents are limited to $35,000 in overtime annually.

Border Patrol Deputy Chief Ronald Vitiello says patrolling the border can be an unpredictable job that requires longer hours from agents.