WIKI

Trading Posts act a bit like a market, but are private businesses. Assigning yourself or a worker to 'Sell Goods' at a trading post will allow you to sell any goods in the inventory directly to customers.

When using automation at a business you can tell its carts to send goods straight to your trading posts.

Once the 'Caravans' upgrade is applied you will also be able to create caravans using a horse cart, this allows you to send goods off the map for higher profit.

Applying the 'Carriages' upgrade will allow your trading post to act as a kind of 'taxi hub' and allow you to buy carriages and assign carriage drivers. NPCs can then hire these for rides around the map.

There is also a ‘Cart Logistics’ upgrade that allows you to setup trade routes. You can use trade routes to automatically haul specified goods between different buildings at a regular interval. For instance you could setup a cart to go around to different businesses and collect goods then drop those goods off at sheds.

Trading Posts are usually used as a supplementary business to sell your goods directly to customers. However, they can also be used as a solo money maker; by watching the markets and buying overstocked goods, storing them until they're needed, and then selling them directly to people.