I don’t agree with your argument that lots of transit agencies is okay providing the boundaries are logical. (Apologies in advance for the lengthy comment.) A bank of hills or a water body means that there are limited points of access across the boundary, called chokepoints, and this in turn means people are used to going out of their way to cross that point. That means, in turn, that a well-placed transit connection point adjacent to the bridge or pass is an easy place for transit agencies on the two sides to converge. An obvious example of such a chokepoint is the Golden Gate Bridge. You have a local agency on either side of the bridge (Marin Transit and Muni), so you might imagine them ‘converging’ at that point; but that would imply that a journey between Marin and San Francisco would require a forced transfer at the bridge. That would be an unnecessary inconvenience, which is why we have a regional transit agency (Golden Gate Transit) that provides continuous express service between three counties, without an awkward forced transfer at the bridge or any other chokepoint. That’s great, but the problem is that Golden Gate Transit duplicates routes served by Muni as it passes through San Francisco; yet it discourages people from using the bus for local trips within SF the city by limiting boardings and offboardings within the city, charging a very high fare ($4.75) that does not provide a transfer to Muni, and not accepting Muni passes. You often see understandably irate tourists who purchased a Muni Day Pass trying to use them to get to/from the Golden Gate Bridge, and being told that they need to pay another $4.75. Once Van Ness BRT is installed the situation will become even worse as we’ll have two Muni routes and six Golden Gate Transit routes using the Van Ness BRT corridor; yet the Golden Gate Transit buses will allow boarding only when traveling northbound, and allow offboarding only when traveling southbound. For Van Ness BRT to be a success Golden Gate Transit and Muni will need to have the same branding, fare system, and pickup/dropoff policy; so either they need to merge, or have a high level of coordination forced upon them them by a regional body such as the MTC. These considerations apply to any place where regional transit and local transit serve the same corridor. The other obvious example in the Bay Area is BART, which duplicates local AC Transit and Muni services in the East Bay and San Francisco respectively, yet provides very limited integration with the local agencies. Very often you see tourists trying to use BART tickets in the Muni Metro faregates, because in almost all cities the subway system is run by a single agency, and the idea of having a single subway station with two lines that requires a different ticket depending on which line you take would be ridiculous to visitors from other countries. Another way of thinking about the geographic issues I've been laying out here is that if you require a connection to continue your trip, there should be a rich payoff in terms of destinations you can reach. The same is true for any hassles created by seams. It's like planes: it's a drag to change planes, and especially to change between airlines, but it's kind of cool, while you are changing planes, to look at the departure planes and think about all the other places you could also get to via this connection. What's more, all those connections are crucial to making your flights viable for the airline, even if you don't use them. That doesn’t make any sense in the context of the SF/Marin interface at the Golden Gate Bridge, as the vast majority of people crossing the bridge on Golden Gate Transit are heading to the Financial District. The only Muni option you have at the Golden Gate Bridge is the 28, which will take you to the Marina or down 19th Ave; hardly a sparkling array of transit options. There is simply no benefit in forcing passengers to transfer at such a location. A better way to think about it is taking a short-haul local flight to a major hub, from where you can catch a long distance flight to a major destination. For example, you might fly from Fresno to SFO and then on to New York. The transit analogy here is taking a local bus from your house to a rail station (the ‘major hub’), and then a train on to the major destination (e.g. the Financial District.) Which begs the question, if that is a journey that many people do on the daily basis (and it is), why not have the bus and rail service run by the same agency? You wouldn’t want to have a connecting flight on a different airline, and neither should you want to have a connecting transit service run by a different transit agency. Some of this wisdom is already encoded in the boundaries of the East Bay agency AC Transit. Near the Bay, the border between Alameda and Contra Costa counties cuts across dense urban fabric, so it would be an awful place for a transit network to end from the point of view of either side. Recognizing this, AC Transit was constructed to unite the two sides of the county line where the urban fabric was continuous, while dividing from other agencies along natural hill and water boundaries, even where the latter are not county lines. This is an important example for many US regions where counties are the default planning units, and arbitrary boundaries drawn in the 19th century (or before) risk turning into walls that sever transit access. Although it’s a good thing that the county line was not used as a transit boundary in this instance, it’s got nothing to do with ‘wisdom’ on the part of the transit agency. Rather it’s a reflection of the service area of the old Key System, which as a private system had no reason to follow county boundaries. There are in fact four AC Transit boundaries which are either questionable or completely ludicrous: the boundary with WestCAT at San Pablo/Pinole, the two borders with Union City Transit at Hayward/Union City and Union City/Fremont, and the border with VTA at Fremont/Milpitas. So clearly the wisdom of not using the county line as a boundary did not extend to the rest of the service area. The northern border with WestCAT is problematic because it creates a minor transit agency that serves just two small towns that are similar in character to neighboring towns that AC Transit does serve, so it would make more sense to merge WestCAT into AC Transit. The three borders with transit agencies to the south result in two transit islands - Union City and Fremont/Newark - which have no continuity with the main AC Transit service area to the north, or the VTA service area to the south. Additionally, both Union City Transit and AC Transit in Fremont/Newark are low productivity because most commuters in these cities head south to San Jose/Silicon Valley rather than north to San Francisco, yet because they do not share a transit agency with San Jose/Silicon Valley, there is no good way to get there on transit. The logical solution here is to merge Union City Transit and AC Transit in Fremont/Newark with VTA, reducing three borders to one and eliminating two transit islands. My two cents: I would group the existing services into the following two transit agencies: Bay Area Transit = Muni + BART + AC Transit as far south as Hayward + WestCAT + SamTrans as far south as the city of San Mateo + Golden Gate Transit & Ferries + SF Bay Ferry Silicon Valley Transit = VTA + Union City Transit + AC Transit in Fremont and Newark + SamTrans as far north as Belmont + Dumbarton Express This organization is a reflection of the fact that the Bay Area is essentially two metro areas close together, one centered around San Francisco, and once centered around San Jose; and that although some people do commute between the two metro areas, the vast majority do not. It also somewhat reduces with the political issues that would occur when centralizing transit in the Bay Area. San Jose would not accept a transit agency run from San Francisco, and visa versa; so a division between the two metro centers is made, and is made as cleanly as possible based on existing commute patterns.