Merseyside Police acting assistant chief constable Stuart Kernohan said: "This co-ordinated approach will ensure that no matter where you are in the North West the chances of being caught if you drive when over the alcohol limit are extremely high - there really is no hiding place.
"If you break the law and drive over the limit you not only run the risk of disqualification and a criminal prosecution, but you risk your own life, as well as the lives of other road users."
Cllr Mike Doyle, executive member for Safer Communities in St Helens, said: "The scale of this campaign shows that the Merseyside Authorities' partnership is stronger and more determined than ever to tackle drink-driving.
"The message couldn't be simpler. Don't drink and drive."
The campaign is part of the Department for Transport's THINK road safety initiative.
Road safety minister Stephen Ladyman said: "The summer months see an increase in drink drive casualties and its essential motorists remember that if they're going to drink they should get someone else to drive or leave their car at home.