Hello, I am someone who went to school for archaeology in the US and has done archaeological field work. My specialty is the American SW, but I do have a general educational background.

I'd like to say that answering this question is difficult is because of how vague it is. Which American-Indians were less interconnected than which Europeans? I will attempt to dispel that general myth, but as for the advance of technology, I would highly recommend reading 1491 by Charles Mann as he does an excellent job explaining the difficulties with that question and the assumptions that it makes.

On a general scale the lack of knowledge is a major effect on the interconnectedness that we (as in popular history more than academic) know of in the US. The pre-colonial population suffered a mass extinction event from disease, followed by and alongside centuries of genocide, displacement and forced cultural assimilation and annihilation. Because of this, much of the verbal history has been lost forever. We do not have contemporary extensive texts describing the trade networks of North America like we do in Europe. The Maya did have an extensive library, but thanks to efforts of the Spanish three or maybe four books survived. Most of our information on pre-contact trade comes from archaeology.

Next I would like to argue that pre-contact America was just as interconnected as Europe. The first is on a major scale. One of the best ways that archaeologists can study the movement of people is through their material culture, i.e. the things they make. And an excellent material to track is copper.

Copper was mined from areas in modern Northern Michigan. It had a wide variety of uses, but what makes it so special is how far it spread. Copper objects made from mines in Michigan found it's way to Mississippi, Florida, and even the American South West. These were likely transported by river, as waterborne trade was the dominant method for moving goods until the locomotive came around.

To put this in perspective, an ancient trader, taking their copper from northern Michigian, to Florida, via the Mississippi and then the Gulf, would make a voyage of over 2000 miles. In comparison, the distance between Paris and Moscow is about 1700 miles. And this trade of copper was not a rare event. Pottery, Obsidian, and certainly other items that we cannot find material remains for like foodstuffs and hides, also were traded across what is now the modern US.

On a much smaller scale I'd like to discuss how we still have so very much to learn. Modern day Florida is full of waterways. And water is an excellent medium for trade. The early railroad industry's biggest competitor in the US and the UK was canals. And it wasn't until more developed, more powerful and faster locomotives came along that the governments fully supported them instead of canal building.

Why is this important? Because archaeologists have been studying Florida's waterways for the past few decades and they've noticed that quite a few of these waterways are unusually straight, and uniformly wide. Archaeological work has been done on some of these canals and concluded that they were built by pre-contact civilizations, dredged by hand.

These canals would have been built at an immense cost in human labor, but would have connected more inland populations with the sprawling trading and political networks.

I hope that gives you a better picture of just how interconnected pre-contact America was. My response of course leaves out things like the complexity of the Maya kingdoms, or the sheer size of the Inka empire and their terrifyingly impressive road network and economic model. And again, I highly recommend picking up a copy of 1491, it's very well written and an excellent introductory text.