Cotton is one of 31 Rare Resources in the game and available from the beginning. It appears as a brown-white field representing a cotton plantation. Like all rare resources on land, cotton can be obtained by sending a Merchant from the Market to the resource location. Cotton provides the following benefits:
Note: Despite the description, Cotton actually increases the current production progress by 25%. This is equivalent to a production time reduction of 20%, not 25%.
The decrease in production times can be quite significant, especially when playing a more combat-oriented game, effectively allowing you to field five units in the regular time of four. Most infantry has a regular base production time of ~15 seconds per unit, thus is created at least (see below) 3 seconds faster. Cavalry units (regularly 15–20 seconds) gets a decrease by 3–4 seconds, ships (regular 12–24 seconds) by 2.5–5 seconds. Note, that production times for combat units ramp up (like resource cost) with each unit of the same type the nation already has. Also, a cotton resource near the starting location offers a good way to boost initial Timber production and to compensate the lack of timber on some map styles (Great Sahara, African Watering Hole, etc).