New research from Carfax indicates a sizable number of previously flooded vehicles are on the road or up for sale in the U.S.

More than 271,000 cars reported as flood damaged by a state’s department of motor vehicles, insurance companies or other entities are back in use. That’s a nearly 30-percent increase from 2013, Carfax said.

Recent flooding in Louisiana is fresh in people’s minds, and in fact that state comes in at No. 10 among the top states with waterlogged vehicles.

Here are the states with the most:

—Texas: 43,000

—Pennsylvania: 20,000

—Florida: 17,000

—Kentucky: 14,000

—Illinois: 13,000

—South Carolina: 11,000

—Michigan: 11,000

—New Jersey: 10,000

—New York: 9,000

—Louisiana: 9,000

“Flooded cars are a buyer’s worst nightmare,” said Larry Gamache, communications director at Carfax. “They’re ticking time bombs because when you least expect it, the electrical, mechanical or safety systems on these cars will fail, often without warning. Consumers everywhere need to be vigilant about checking a vehicle’s history for flood damage and getting a pre-purchase inspection to avoid buying cars that rot from the inside out.”

Powerful storms and epic flooding in major areas are creating more opportunities for professional con men to clean up and resell flooded vehicles. Research has shown it takes only a few hours to restore them cosmetically, at little cost to the criminals. However, buying one of these dangerous cars costs unsuspecting consumers thousands.

“A customer was requesting a loan on a used car, so we ran a Carfax Report as part of our underwriting procedures,” said Willie Macko, president of PriorityOne Bank in Mississippi. “We discovered that the car had been a total loss and the title was branded as a flood vehicle. By using Carfax, we were able to save both our bank and our customer a lot of money.”

Carfax says that these are telltale signs a vehicle has been in a flood:

— A musty odor in the interior, which can sometimes be covered with a strong air-freshener

— Upholstery or carpeting which is loose, new, stained or doesn’t match

— Damp carpets

— Rust around doors, under the dashboard, on the pedals or inside the hood and trunk latches

— Mud or silt in the glove compartment or under the seats

— Brittle wires under the dashboard

— Fog or moisture beads in the interior lights, exterior lights or instrument panel

Consumers may check for flood damage free of charge here.