Let me preface this by noting that I have no answers to this problem, only questions. This is a problem that I've been mulling over in my own work, which mostly relates to the political place of the urban plebs, for some time, but which I have not yet managed to work out in a satisfactory way.

The question of the rural and urban plebs as political entities is one that is quite well-known to students of the period, but which is, in my view, unsatisfactorily treated. At the most obvious level we can quite definitively say that yes, such a political divide did exist within Roman Italy in the Republic, and we may point to the Social War as an indication of this tension. The problem is, the source of this tension is not clear. Since I have no intention to reinvent the wheel, a discussion by /u/LegalAction on the issue of the Social War, which was a focus of his dissertation, can be found here. No matter what the particular cause of the Social War, clearly there was some major political schism between the city and at least many of the Italians, or more likely a series of disagreements according to various groups. There's a further problem here, which was identified at least as early as Badian's Foreign Clientelae, in that the Italians themselves had an aristocracy and had city populations--they weren't all rural. We see this distinction reflected sometimes in our texts: Appian, for example, divides up the Italians and the Etruscans and Umbrians (not yet then called "Italians") when discussing their role in the plot to murder the younger Drusus.

So to begin with the Italians were not a unified group of people. They contained their own aristocracy within their own communities, which were politically and culturally distinct from each other and within which we find both rural and urban centers. What of the urban plebs, then? Surely a smaller body like the urban plebs should be relatively unified, and our sources usually profess ignorance of any sort of social division within the urban body, treating it as a sort of many-headed beast with one body (or perhaps a many-bodied beast with one head). But knowledge of political divisions does quite clearly pop up. Cicero, for example, acknowledges the existence of classes of tabernarii and mercenarii when he speaks of P. Clodius' followers--the one is a class of shopkeepers and skilled tradesmen, the other a catch-all term for day-workers. The city plebs consisted mainly of semi-itinerant day-workers who eked out a living chasing what work they could. Barely able to feed their families, they migrated not only through the city seeking work, but seasonally moved to and from the rural districts, where their labor was appreciated during the busy planting and harvesting seasons. There also existed, within the same capite censi, a class of shopkeepers, artisans, and other skilled tradesmen. That these men were very different is quite clear. They could afford permanent lodgings and even, already by the middle of the first century, to set up public inscriptions. The high proportion of freed slaves, who would have been likely to learn a trade while in their masters' households, among this plebs media is quite well attested, and with it comes the realization that freedmen, in the city or in Italy, were enrolled only in the urban tribes. While the itinerant plebs were probably engaged in politics on sort of a rotating basis as the opportunity presented itself, these men had more of an opportunity to engage more regularly. So what are we to make of these divisions (and doubtless many more for which we have less evidence)? It's hard to say, but just as with the Italians it's clear that there was a lot of diversity in the urban population, which was after all the largest urban population in the history of the world up to that point.

For Appian the cause of political violence is fairly routinely to be found in quarrels between the rural and urban plebs, whom he often refers to after the Social War as the "old citizens" and the "new citizens." That he means more than the nobiles by this is clear, as he often modifies his characterization of the "old citizens" or "cityfolk" with τὸ πλῆθος, "the plebs" and other distinguishing terms only applied to the non-aristocratic body. In this description we find clear signs of an understanding of a division between urban and rural politics that is found elsewhere. Apart from case-by-case issues like the division of Italians into all the rural tribes or of enfranchisement we begin to see some patterns in legislation offered by tribunes and other politicians to different groups. Appian and Plutarch both seem to attest that colonial foundations were generally seen as placating the urban plebs and that the Italians were not fond of them, as they might encroach on their own rights to the ager publicus. This is not always the case, however--Caesar's decemvirate founded many colonies in Italy settled entirely by Pompeian veterans, and despite (or rather, in part because of) these colonial foundations he was despised by the urban plebs in his consulship. The urban plebs strongly favored grain bills. It is easy to imagine why--the unstable wages of the urban day-worker were not enough to provide for himself and his family without some margin of assistance--but interestingly I have found no evidence that the rural voters cared one way or another. Perhaps this is to be expected too, since it's not really their problem. I don't know. P. Clodius' leges Clodiae give us a good idea as to how urban support throughout the plebs could be secured: Clodius established both a grain bill (which was unassailable by his enemies) and a lex de collegiis which protected the social organizations that so much of the plebs media were involved in. Of the four leges Clodiae, however, and of Clodius' later proposed legislation (such as the distribution of freedmen into all the tribes) we see no efforts to pass any legislation traditionally seen as "rural." Is this suggestive of a movement away from divisive politics between the urban and rural voters? Of a loss of political points to be scored by siding with rural questions thought by most of the senatorial class to have been settled? Perhaps, but as late as the Catilinarian crisis we see that the Italians were still divided from the city. The urban plebs, our sources repeatedly attest, were indifferent to Catiline's program. The debt relief and land distributions, on the other hand, must have been welcome among not only the indebted senatorial elite to whom Catiline appealed but also among small-time rural landowners buckling under the weight of their enormous loans. Perhaps it is no small wonder, then, that we find Italian cities at Faesulae, Capua, and elsewhere rising up in favor of Catiline while the city (helpfully policed by Cicero's troops) sat mostly idle. I don't know. What is clear is that the Roman plebs as a political body were clearly quite diverse. Roman Italy was a collection of hundreds of little ethnicities that maintained some degree of identity for some time, and the city itself was possibly the most diverse population the world had ever known (Alexandria might dispute me). Not only ethnic diversity, but social, economic, and consequently political diversity must have been evident everywhere. The constant wrangling between rural and urban voters evident in our texts is maybe indicative of some general political schism between the city and countryside, and no doubt there was no small degree of disagreement there--one needs only look at the votes of the tribes to see a major distinction. But whether the impression in our texts that this was the big division between the plebs is in fact valid or a sort of teleological result of the way things played out or something like that...that I cannot say for certain. Quite clearly serious divisions existed politically and socially within the city and within the Italian population, as well as between those two larger groups. Our evidence is unfortunately lacking there, and interpretation is made difficult. Clearly tribunes had to tiptoe around various lines drawn in the proverbial sand across all kinds of divides--where were these divides? Is the urban/rural one that may exist really the most important?