(NewsNation) — More drivers have been using illegal license plate changers and obstructers to avoid paying automated tolls, a tactic cities say is costing them millions.

Those trying to avoid being charged are using remote-controlled electronic curtains and flippers to cover their license plates, the Port Authority of New York and New Jersey said. 

The flipper is used to change one side of a license plate to a completely different plate. For example, a Texas license plate flips to a New York license plate. Another option is the electronic curtain, which lowers a cover over the license plate at the click of a button. Both can be bought online.

Officials say it’s costing government agencies millions.

Since the widespread use of automated camera tolls at the beginning of the pandemic, New York City has seen a 137% rise in toll avoiders, the Wall Street Journal reported. It has cost the city more than $20 million in 2023, according to data from New York City’s Metropolitan Transportation Authority Bridges and Tunnels.

Earlier this year, the Port Authority said it recovered more than $25 million from toll evaders last year, which is up 14% from the previous year.

In Dallas and the San Francisco area, authorities believe they’ve lost out on more than $33 million combined.

“Maybe they weren’t all deliberate, but they do add up,” said John Goodwin with the Bay Area Metropolitan Transportation Commission.

Now, there’s a big push to crackdown on these sneaky drivers.