Interstate 18

Interstate 18 is a major Interstate Highway located within the northern portions of the Iberian Peninsula in northern Spain. Although it is nominally an east–west road as it is even-numbered, it follows a more northwest–southeast alignment. Its western terminus is at I-30 in Bilbao, Spain; its eastern terminus is at I-14 in Zaragoza, Spain. I-18 connects the cities of Barcelona via I-14, Zaragoza, and Bilbao.

Route description
Interstate 18 starts at its western terminus with I-30 in Bilbao. From there, it runs between the Cantabrian Mountains and the Pyrenees as a north-south alignment until reaching I-20.

Auxiliary routes
I-118 is an north-south auxiliary route running from I-18 from the north to Pamplona.