The colonies of New York, Delaware, New Jersey, and Pennsylvania comprised the middle colonies. The Hudson River and the Delaware River were two of the major waterways. This area also has adequate maritime harbors along the shore. The terrain varied from coastal plains to piedmont (rolling hills) to mountains further inland. It was not until after the Revolutionary War that the first bridge over a large river was built - the Delaware Bridge at Wilmington, Delaware. The middle colonies had their origins as separate settlements long before they became one nation. They included parts of New York, New Jersey, and Pennsylvania. Although they shared many similarities, each colony had its own government and laws they could decide what role, if any, they wanted to play in the emerging United States. There are three types of harbors - natural, artificial, and combined. Natural harbors are areas where rivers meet the ocean and contain deep waters close to the land. These are the most peaceful places to dock your boat but they can be difficult to find because only a few get washed away by storms every year. An example is Cockburn Cove on Cape Cod. Artificial harbors are lakes or channels dug by humans that allow boats to dock safely even when water levels are low. The Lake Champlain Maritime Museum in Vermont is located in a former industrial canal lock. Combined harbors are the combination of an artificial harbor with other types of facilities such as marinas, warehouses, fuel docks, restaurants, etc.