I wonder if trade routes are the cash cow?

[stormwriter]

So, you can get +2 trade routes in all coastal cities with The Great Lighthouse, you get +1 from Corporation, +1 from Currency, and +1 from the Free Market civic.
I checked, and my capitol's trade routes were giving me +10 each. Then, i switched to Free Market, and yep - there's another +10 commerce coming in. Sounds good to me!
I don't know what that amount is, or how to increase it, but I'll take five trades routes, thank you!
Sounds like something i'll try and get in the future, but the computer gets The Great Lighthouse pretty dang quickly, especially if i'm busy building the Oracle or the Parthenon.

Oh wait... color me stupid... I just read that the Corporation obsoletes The Great Lighthouse, so there goes one trade route.... So, the max is four per (coastal) city.

I figured out you can trade on the COASTline with the Sailing technology, but the traders must share the same coast. You can trade over the OCEAN when you research Astronomy, which lets you trade with civs on continents far away.

This Civ4 should be a college course. If i put as much effort into my job as i did this game, i'd maybe move up the ladder more quickly.
Mmmm, promotions... Medic 1, or Barrage 2?

[Blake]

Yes I've come to appreciatre the Great Lighthouse muchly. It's easy to get too even on higher difficulty levels.

Even fairly early in the game trade routes can give 4-5 gold each (that's with harbors), so the Great Lighthouse in effect adding as much commerce as 2-3 free specialists per coastal city, that compares very favorably with other wonders.

[QuestGAV]

For further evidence on the greatness of trade routes check the Harbor thread. Remember that your trade routes are going to become more valuable if you have open borders with more civs as well. Diplomacy & economy go hand in hand.

[Fosse]

Originally posted by QuestGAV
Remember that your trade routes are going to become more valuable if you have open borders with more civs as well. Diplomacy & economy go hand in hand.

From my experience this is not totally true. It seems that there exists one most profitable trade route for every city, and that said city probably exists in a foreign country on the other side of the map.

If you have open borders with the country that has that city, then you are making the most you can from trade. Having more open borders doesn't really matter.

In one game where I had many Open Borders agreemets, every single trade route I in eight or so different cities went to Egypt. From a commerce standpoint, the only Open Borders agreement that meant anything at all was the one with Egypt.

This is a change from SMAC, where each city traded with the most profitable city from every faction you had Treaty or Pact with. In that case every treaty was indeed more commerce. In Civ IV it is potentially - but not certainly - more commerce.

[QuestGAV]

The speculation there is that the trade routes are paired off via a global list. So your biggest cities will be paired with other big cities and your small ones will go with other small ones. If your civilization is significantly more developed than most of your rivals or you have an open borders agreement with a large empire and a small one, you might see what amounts to a monopoly for the most part. However, with 3 equal sized countries in open borders you'll have a much bigger benefit than just trading bilaterally.

The other possibility for the situation you saw is that the non-Egyptian civ you had open borders with was mercantilist. Otherwise, the more countries you can trade with should have a trickle down effect across your empire (and theirs - so there may be reason not to trade with an empire you intend to swallow).

[Fosse]

It was a huge map, with 18 civs. The game bogged down so I quit playing it, but we hadn't advanced to mercantilism yet. I don't recall Egypt's relative power, mine was in the middle.

It could just have been that Egypt's cities were all the best partners for me, and I noticed because it was so unusual.

Here's another trade route question: If Washington's trade routes are to Persepolis and York, for example, does that mean that York and Perseoplis each have one trade route to Washington?

If so, will they be for the same base amount of commerce?

[khumak]

Trade routes are by far your biggest source of income later in the game. My best coastal cities late in the game are pumping out almost 100 gold per turn from trade alone and considerably more when you include towns, banks, etc. It's not unusual to have more than 1000 gold per turn coming in when I get into the 1800s so I don't worry about shields. I just pay cash for most of my buildings. For inland cities trade is FAR lower because you aren't trading with cities across the globe like your coastal cities are. It seems like the amount a trade route is worth is proportional to distance * total income.

[Yuufo]

I noticed that the foreign cities I'm trading with belong to leaders who like me (pleased or more). I have other neighbours, with Cautious relations and peace traity, as well as a trade network with them. However they don't trade with me. Is there a rule that allows trade only with "good" friends?

[mgdpublic]

What determines the amount a trade route brings in, just distance? Is there anything I can do to boost individual trade route commerce rather than just research for more trade routes? Also, is trade route considered gold or commerce and if its the former, is it effected by banks?

[Cardozo]

Distance and size. To encourage distance and choice of cities to trade with be sure to send out a bunch of caravels on auto-explore.

Airports also give an extra trade-route in the late game and I think (but am not sure) that inland Airport routes are not limited to the continent the city is on like the other trade routes are.