Commerce () is one of the three basic economic inputs found in Civilization IV. It is produced by trade routes, and by tiles when they are worked by population in a city. See the Production article for more info.
Commerce should not be mistaken for gold (). Gold is produced from commerce (if slider settings indicate that), and gold is also produced by certain buildings. Commerce is produced only by tiles, trade routes, and a single building: the Palace.
Commerce is produced inherently by the following types of terrain:
- Rivers (in adjacent tiles)
- All water tiles (ocean, lake, coast), except if they have ice
Commerce is generated by these tile improvements:
Many resources generate commerce. Some resources add commerce to their tile even before they are improved:
Many resources add commerce only when they've been improved with the particular improvement which unlocks the resource: