Police spot a vehicle they deem suspicious because of out-of-state license plates, erratic driving or other common tells. The police then follow the vehicle and watch for traffic violations to justify the stop.

The officer talks to the driver and passengers separately to see if they have different stories about their trip. They look for nervousness, pounding arteries, an abundance of hanging air fresheners and suspicious-looking compartments.

The officer asks for consent to search. If the driver doesn't grant permission to search, the officer calls in a drug-sniffing dog. If the dog signals on drug scents, a search is allowed without the driver's consent and with no warrant obtained.

Police look for cash in unusual compartments, like an extra gas tank or battery compartment.

The driver is released without criminal charges — and without the cash they were carrying. Though driving with large amounts of cash is not a state crime, police can seize the money if evidence ties it to a drug crime. Prosecutors take the seized cash to state court to approve sending it to the U.S. Department of Justice, as part of the federal Equitable Sharing Program. The Justice Department keeps 20 percent of the value of the property and sends the rest back to state authorities.

Missouri police have spent the seized money on a variety of items including renovated jails, new police cars, exercise equipment, courtrooms, military equipment and helicopter equipment.