One of the distinctive elements of the Roman world is undoubtedly represented by the road network, which was structured following the broadening of the territories controlled by Rome. The result is a fairly rigid system, but still sensitive to the changes of the overall political situation. An example of these variations can be appreciated in Padan Italy. Taking a look at the itinerary sources, the main route linking Northern Italy to Rome is constituted by the system via Aemilia-via Flaminia. However, during the 5th century, when travelling from Lion to Rome, Sidonius Apollinaris followed a new itinerary. The use of that route, anyway, did not derive from Sidonius’ personal choices, but from changes occurred within the cursus publicus. What caused those variations can be seen in the alteration of the overall political situation, which led to prefer waterways instead of land routes. This article illustrates this modification, showing also the consequences it brought to the via Aemilia, and, more generally, to the trans-Apennine connections.