Gardaí have been gearing up for one of the biggest traffic policing operations in the history of the force.
Several hundred vehicles, patrol cars, motorcycles and unmarked cars, and hundreds more gardaí on foot, have been assigned to the northwest for the Irish section of the World Rally Championship.
They will be backed by more than 2,000 marshals and volunteer stewards who have been recruited locally and overseas.
The rally, one of a series of contests around the world, started at Stormont yesterday and moves to the western Border counties for 19 more stages today, tomorrow and Sunday.
Up to 150,000 people are expected to turn out as the rally passes through Sligo, Donegal, Leitrim, Fermanagh, Tyrone, Cavan and Roscommon.
Gardaí had held top-level conferences to plan policing of the event and the traffic corps gathered at Finner Army Camp, near Bundoran.
A senior Garda spokesman said: "For obvious reasons we cannot be specific about the numbers of vehicles involved but it will be a lot. It's the biggest operation of its kind ever in the northwest." He added: "In addition to the marked cars and motorcycles there will be a number of unmarked cars patrolling the roads. It will be both an overt and covert operation."
The rally's final stage will be on Sunday afternoon in Mullaghmore, Co Sligo.