More than 150 vehicles were stopped, 19 people arrested and 14 vehicles seized as part of a police operation on both Severn bridges on Thursday.
Vehicle inspectors were on patrol throughout Thursday
Some 200 police officers from four forces were involved in the operation which scanned the number plates of all vehicles crossing the bridges.
This included 60,000 vehicles crossing the M4 Severn Bridge and 20,000 travelling over the M48 bridge.
A police spokesman said the day had been a great success.
Police used Automatic Number Plate Recognition (ANPR) units which alert officers to any crime the vehicle or its occupants are wanted for.
Chief Superintendent Lawrie Lewis said: "Police from three constabularies, working on both sides of the Severn Crossing have caught up with 19 people who had, until today, been flouting the law.
"We have made arrests for offences including breach of bail, theft of motor vehicle, possession of class A drugs, being in possession of an offensive weapon and fraud.
"Fourteen vehicles have been seized for offences including having no insurance and dangerous driving."