This is an idea that I really liked from Civ2 and was sad to see it absent in C3 and C4. The greatly improved trade system made its main function obsolete, and the elimination of Wonder rushing in Civ3 put the nail in the coffin. But that doesn mean it should be buried completly. Of course it would need tweeking for Civ4, but I think it would add an interesting dynamic to the game. Caravan: Requires Currency (like we needed another reason) Str - 0 Move - 2 Cost - 50 (f/p like Workers and Settlers) Upgrades to Freight Frieght Requires Refigeration Str - 0 Move - 2 Cost - 100 f/p Production costs are just estimates, testing would be required to set actual amounts. F/P is used to allow both high production and high food cities to create these units. These units would be placed in one of your cities. They would have the options of: Food Supply Line: Generates 1 Food for 'current city' at the cost of X Food from 'originating city'. Production Supply Line: Generates 1 Production for 'current city' at the cost of X Production from 'originating city'. The X would be variable depending on which unit is used (Caravan would be higher than Frieght of course), and the distance from the originating city. A neighboring city would be a 1-1 trade for either unit, a city on another continent would be substantially higher. Also, the Food/Production is taken away from the base F/P of the city, ie before multipliers such as Forge are applied or the storage effect from Graineries are calculated. Now the kicker is that setting up these routes doesn't consume the unit, it mearly puts it into sleep mode. If you want to cut the route then you just instruct the unit to stop trading. Then you can either keep it there to turn on later, or you can move it to another city to send your supplies there. This would give the player a great deal of flexibility in placing and improving their cities. This would lead to the ability to truely specialize cities. For example, a food generating city could support a massive production city, which could in turn send supplies to help build projects all over your empire, or focus them in one city to help build important improvements quickly.