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It is important to connect with your neighbors. You can connect Roads, Subways, Rails, Highways, Water Pipes, and Electric Lines with neighboring towns. Usually connecting with your neighbor will cost extra simoleans.

[edit] Neighbor Deals

In SC3K and SC4, you can make deals with your neighbors. These are to Buy or Sell either Power, Garbage, or Water.

• Buy: This is when you buy Power or Water. This will cost you based on how much your grid takes from the neighboring cities. This can also mean taking Garbage from another City and storing it in your landfill system. You get money based on a set amount of Garbage that you import - unlike Buying Power or Water, you have to agree to take more or cancel the contract.
• Sell: This is when you sell Power or Water. Unlike Buying Power or Water, you have to agree to sell more or cancel the contract. This can also mean exporting Garbage, in which you will have to pay a set amount based on how much Garbage you have been exporting.

Neighbor Deals require Power Line connections (for Power Deals), Water Pipe connections (for Water Deals), or Road connections (for Garbage Deals) and are proposed by neighbors in SC3K - you cannot start them - but in SC4, as you control both cities, you may begin a deal at any time. There is a penalty fee that you are charged if you cancel the deal. When buying, you only have to worry about destroying all your connections. When selling, you will sometimes run out of the commodity and the deal will automatically close, thus causing you to pay the penalty. An interesting tactic is to buy a commodity and sell the same commodity, thus creating a "safety net" in which you will never run out (when Buying, your neighbor wont ever run out of whatever your buying from them) of what your selling.