American Silk Road?

Trade, even along the real Silk Road, tended to be local. The goods might start out in China, but did not go on a camel that carried them all the way to Persia (or visa versa). They made their way to the market in the next large trading center, were bought and put on a new camel before traveling to the next market. The goods worked their way along the Silk Road until they reached their final destination. While there was not as large or well designated a trade north and south in the Americas, it did exist in much the same way.

There were trade routes in North America but not all the way down into Central. These were prior to 3,000 years ago. Shells from the Gulf of Mexico were found far to the north, flint for arrowheads was found hundreds of miles from the geological areas they originated in.

Here, exactly what you're looking for -- google the words "native american trade routes" and click on 'images'. You can see only one route is shown going down into Mexico but there's an extensive known trade circuit across American and up into Canada.

How can you claim to be an anthropologist, but be oblivious to the trade networks as made evident by the goods found thousands of miles from their origin? This sounds more like "I read some stuff and took a course once," rather than something a person who has studied the issue might be asking.

A quick journal search on "Pre-columbian Trade routes" will realize hundreds of papers on this subject.

Maize cultivation alone proves an extensive trade network.

There was a lot of trade across North America. There's a bunch of research on this that you can find both in some popular books on pre-columbian Native America and in scholarly works. For example, archaeologists have found remnants of seashells far into the interior. So we know that there was extensive trade going on across the continent of North America. Personally, I don't know if there was a lot of trade between North and South America. The problem is that there are parts of Central America, mainly down in Panama, which are extremely difficult to pass through.

The Inca were the nearest in South American region.

Some similarities between the Mesoamerican and the Andean cultures suggest that the two regions became a part of a wider world system, as a result of trade, by the 1st millennium BCE. A maritime exchange system stretched from the west coast of Mexico to southernmost Peru, trading mostly in Spondylus (bivalve molluscs), which represented rain and fertility and was considered the principal food of the gods by the people of the Inca empire.

Could be but they's also have to be mariners cause Panama is not easy to walk through.