The N81 is the only major national road emanating from Dublin that is a national secondary rather than national primary road.
The official definition of the N81 from the Roads Act, 1993 (Declaration of National Roads) Order, 1994 , Irish Statute Book (irishstatutebook.ie). (HTML file). Retrieved 2010-02-14. – Department of Transport. Retrieved: 2011-02-14. states:
<u>N81</u>: <u>Dublin — Closh Cross, County Carlow</u>
Between its junction with N11 at Church Lane in the county borough of Dublin and its junction with N80 at Closh Cross in the county of Carlow via Dame Street, Cork Hill, Lord Edward Street, Christchurch Place, Nicholas Street, Patrick Street, New Street South, Clanbrassil Street Lower, Clanbrassil Street Upper, Harold's Cross Road, Terenure Road......