I don't have sailing, and I don't see how the two rivers are connected, yet my two cities have trade routes

Either their culture is one "blob" instead of two "blobs" or the river right next to your northern city is making trade with the southern due to being on the southern's BFC.

sailing is not necessary for rivers inside your borders. But this does not explain the current case. I don't know.

However, I advise you to build more workers ;)

Could you provide a save ?

Perhaps one of the tiles counts as a double riverside.

I guess it's the tile south of the silk, it connects Uppsala River with Nidaros River via coast, all within your cultural borders, so Sailing is not required.

Could it not be something as simple as it can follow one river down, get to the coast, follow it round and then go up the other river.

Sailing allows trading on Coast's and river's after all, no?

Could it not be something as simple as it can follow one river down, get to the coast, follow it round and then go up the other river.

Sailing allows trading on Coast's and river's after all, no?

There's only one problem with that theory, but it's a big problem ...

I don't have sailing

Could the river be coast-side? Its kind of a big stretch, but if the game allows that maybe the river goes all the way around the coast.

Dan's explanation is the only sensible one I can think of.

Dan's explanation is the only sensible one I can think of.

Seems that way. I don't think it should work like that, but it must.

If Tecibbar can post a saved game, we could test it by planting an enemy city on the adjacent hill (where it will steal that flood plains tile) to see if that shuts down the trade route.

Tecibbar might not want to do that test himself, since it would involve the World Builder, which might spoil the game.

I didnt think you needed sailing to connect resources by river. Well not in the games i play anyway.

I didnt think you needed sailing to connect resources by river. Well not in the games i play anyway.

Outside your cultural borders you do.

^^In BtS . In warlords and Vanilla you don't need sailing for trade route connection on rivers.

This has always been my experience actually. I have seen this situation multiple times, and I always chalked it up to some sort of rudimentary pre-sailing boats. =P

The other possibility is that he's working tiles that are on the river.

Of note, in BTS you need sailing to trade on rivers, where as in vanilla you do not. (rolo beat me to it!)

More example,

in the screen shot below, my city has access to corn.

More example,

in the screen shot below, my city has access to corn.

That one I can't explain. :confused:

The corn tile and the the city tile are both riverside and they are adjacent, so the game assumes there is a river passing by both.

I'll try: the Corn is connected to the western river, but not to the city or the eastern river directly. However, connectivity is a bit special for river networks. The Corn tile is actually a double river tile since it is also adjacent to the gridline intersection that marks the spring of the eastern river. So the connection goes: Corn - western river - double river Corn tile - eastern river - city.

Testing this stuff is a bit tricky because river network connectivity seems not to be automatically updated after terraforming via world builder.

Here is your example with the network stretched out and excluded coastal trade:
http://i294.photobucket.com/albums/mm105/DanF5771/RiverCon.jpg

Edit: r_rolo1 was quicker :).
Edit2: But the city being riverside is not enough, the connection is lost after the river section south of the stone is deleted in the modified example. This sort of connectivity is also the true explanation for your first example of the Nidaros - Uppsala network. Here it's the tile north of Nidaros.

Nice sumup Dan. :)

That's odd how it works that way, since the tiles by the headwaters are NOT river tiles. No coin, no hammer from levee, and if you build your city there, it says it's not on a river. I'm not doubting your conclusion - you proved it by deleting the river - just stating that it is completely inconsistent with everything else.