PORTLAND, Maine (AP) — Maine Turnpike Authority data shows the agency is owed more than $800,000 in unpaid tolls dating back to 2013.

The Portland Press Herald reports most of the money is owed by out-of-state vehicles, including commercial trucks.

The turnpike authority says it can be difficult to find violators because most states won't share information on drivers.

Unpaid tolls makes up a small portion of the authority's annual toll revenue, but the actual amount owed could be much higher because tollbooth cameras aren't able to read dirty, obscured or missing license plates.

Maine, New Hampshire and Massachusetts have an arrangement regarding the prevention of vehicle re-registration for those that owe tolls.

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