Repeated Commodity Trade Strategy

[Adam Smith]

Bird:
If you finish a discovery by producing science, any excess rolls over into the next discovery. If you finish a discovery by establising a trade route, any excess is lost.
Carolus Rex:
I have version 2.42

[Carolus Rex]

I've noticed it, but I thought it was a bug (I'm playing version 1.06). Hides is the only commodity I've seen it happen to, but I'll check other commodities more closely in coming games.

Carolus

[EnochF]

I've seen it happen... although I always thought that the city simply started demanding the commodity a turn or two after my freight arrived. I seem to recall once a city of Los Angeles that was always hungry for gold. I eventually bribed the American city of Seattle just so I could have an airport to deliver my gold bullion into L.A. (How does that work, anyway? If you're giving them gold, what are they paying you with?)

[Ming]

I didn't know this! Maybe I'm just not paying attention (very likely) but I have never seen the situation you discribe. About 1/4 the cities you say... I will check this out. Usually I go from tribute to the multi continent trade strategy once the other AI's stop giving me money. And there usually is a gap between the two.
Another great way to cash in big during the early and middle game is to set up a barbarian killing field. Barbs will appear in empty areas and not in heavy city areas. Leave an area that you can control empty. Leave units in fortified defensive positions (defensive and mobile) and wait for the barbs. The barbs will kill themselves on your solid positions, and your mobile units can chase down the kings. It works like a charm... instead of barbarian alerts, I just see "Visa" alerts.

[Bird]

I had a funny feeling this was happening in a game I finished last night, but I had 70 cities and could not remember where previous freights had been sent.

Adam Smith: are you sure "any additional trade-related science beyond what gets you to the next discovery gets wasted?" I thought that once the beaker was full, you discovered a new advance and then the beaker started to fill again, even if the turn was not over.

[Adam Smith]

You can develop a steady and very substantial stream of income and science by repeatedly trading the same commodity or commodities to the same foreign city. Here is how the strategy works.

Once a civ develops trade, each city has three commodities it demands. Once you establish a trade route with a city, 0,1,2, or 3 of the commodities will either become unavailable or will change. For example, a city that originally demands Silk, Gold, and Coal may, after the establishment of a silk trade route, read (Silk), Wine, Coal. () indicates that you can no longer trade the commodity to that city. What you need to find are the cities where the commodities DO NOT change or become unavailable when you establish a trade route. For example, a city that demands Silk, Gold, and Coal will still read Silk, Gold, and Coal after the establishment of a trade route. Repeated simulation with the Cheat feature and in game situations indicates that one quarter to one third of the cities you can trade with will have this property.

Once you identify a partner city whose commodities do not change, gear all your production toward building caravans or freight units to trade with this city. Build (or buy) caravans or freight units in cities that produce the commodities the partner city demands. Home the caravans or freight units to your Colossus city or other big trade city. This is very important not only because it maximizes income, and also because it allows your production cities to repeatedly produce the commodities the partner city demands. Ship the caravans or freight units off in batches of three or four per turn to the partner city. (Any additional trade-related science beyond what gets you to the next discovery gets wasted). Land the caravans or freight units and collect your bonus.

I researched this strategy about a month ago using the Cheat feature on saved games, and I tried it in a full game situation for the first time last night. I had sent out about 12 early trade routes, and identified at least three cities whose commodities did not change or become unavailable when a trade route was established. I selected the closest city, a size 12 Babylonian city six squares west of my continent, and about 12 squares west of my Colossus city (size 18). I dedicated two transports to this trade route so I could be sure of having freight units arriving every single turn. In 1800 I developed Corporation (freight units) and went to work building building freight units carrying silk and gold. In the next 16 turns I developed 15 technologies and added about 25,000 coins to the treasury. Virtually all of this came from trade.

This strategy may eventually wear out. Even though I homed all my freight units to the Colossus city, I now have many fewer cities that produce silk and gold than I originally did. However, you could combine this with other strategies in order to do quite well. For example, try Ming's tribute strategy early in the game, this strategy in the middle, and Xin Yu's Two Continents trading strategy late in the game.