Mud Lake could be wet, dry, marshy, or frozen, depending on the season and the weather, making it a difficult, albeit very valuable, transportation route. In very wet weather the water level in both the Des Plaines River and the Chicago River would rise to the point that Mud Lake was flooded, and travelers could traverse the entire six miles by canoe. Usually, however, particularly in late Summer, it was necessary to pull out canoes at some point and carry them and all supplies around Mud Lake. A key to travel and trade in North America The Chicago Portage allowed easy access, by boat, to almost all of North America, from the mouth of the St Lawrence River to the Rocky Mountains and the Gulf of Mexico. The St Lawrence River divide Until the second half of the nineteenth century water transportation was virtually the only way to move trade goods and people around North America. Therefore, connections between strategic waterways, usually involving portages, held special importance. The importance of the Chicago Portage lies in the fact that the channel cut by the Chicago Outlet River created an easy passage over the Saint Lawrence River Divide, the continental divide that separated what had become the Great Lakes waterway system from the Mississippi River waterway system and, as the illustration shows, opened up almost all of what was to become the United States from the Allegheny Mountains to the Rocky Mountains as far south as the Gulf of Mexico. Early peoples Native Americans had used the portage for thousands of years before the arrival of Europeans. They found the Chicago Portage to be a convenient transportation route between the shores of Lake Michigan and the Mississippi River in the interior. The map shows that the most important trails in the region led to the portage and the several fords near it. The map also shows the Old Portage Long trail that was used when there was insufficient water in Mud Lake to allow traverse by canoe. This trail extended to the southwest to the early settlement of Ottawa on the Illinois River. Since there was usually sufficient water in the larger Illinois River for canoeing, this “Ottawa Trail” was used in very dry conditions when there was insufficient water in the Des Plaines River. The first Europeans By 1673 the French had established a trading post at present day Mackinac Island