Strada statale 4 Via Salaria (SS 4) is an Italian state highway 208.2 kilometres (129.4 mi) long in Italy located in the regions of Lazio and Marche, linking Rome to the Adriatic Sea passing through Rieti and Ascoli Piceno.

After four kilometres SS4 meets Tangenziale Est di Roma and, from that point on, becomes a busy dual carriageway urban road, filled by people leaving or entering the city.

Immediately after, the road returns a single carriageway highway; in fact the subsequent 20 kilometer stretch, from the GRA to Passo Corese, has seen his importance reduced since the 6-lane Autostrada A1 runs parallel to it and absorbs most of the long-distance traffic.

For this reason, SS4 had once a rather rough course from here on, with tight bends and continuous rises and descents; current SS4 is a completely new road (constructed in the 1960s to replace the old one from Passo Corese to Rieti), much more straight and wide, albeit still with a single carriageway.

After Ascoli the road continues towards the Adriatic Sea with a rather winding path, where it ends in a junction with SS 16 Adriatica and the Autostrada A14 in Porto d'Ascoli (near San Benedetto del Tronto).

[1] For this reason, Italian Government plans to make SS4 a dual carriageway road between Rieti and Passo Corese, but around 1.5 billion euros are needed[2] and it is not known when funds will be granted.