Originally running from Tarragona to Bilbao, several segments have been downgraded due to the construction of parallel motorways.

The road heads southeast from Bilbao over the Barazar pass to Vitoria-Gasteiz.

The segment from Luko to Vitoria-Gasteiz has been upgraded to autovía standards.

[4] From Pamplona to Jaca, the Autovía A-21 is being built parallel to the old N-240.

[7] In the last section, between Montblanc and Tarragona, the Autovía A-27 is being built as an alternative to the old N-240.