|To:||Carrickcarnan (border) (J071171)|
|Distance:||89.9 km (55.9 miles)|
|Meets:||M1, N52, R132, R173, R174, A1|
|Route outline (key)|
As with all national roads in the Republic of Ireland, sections of the route may be classified as motorway, and in such cases the national road number is retained, but the prefix letter is changed from N to M to indicate this status. Thus while almost all of the N1 is today classified as motorway (and is therefore signed as M1), the M1 remains, legally and administratively, a part of the overall N1.
The N1 originally began in the very heart of Dublin, at the northern end of O'Connell Bridge over the Liffey, but since 2012 its starting point has been moved north to the Turnapin Interchange (J1 of the M1 / J3 of the M50), and from here the road is classed as a motorway all the way to Junction 18 (Carlingford). Only the final nine kilometres from there to Carrickcarnan and the border between Counties Louth and Armagh retain non-motorway status and are therefore still signed "N1"). Most of the remainder of the original, pre-motorway, route of the N1 through Drogheda and Dundalk has been reclassified as of regional status, principally as the R132.