Answer: What is the oldest city in the Americas?

 Simple questions are

sometimes harder... 

Mythical ancient city by Imagen

... than you'd expect.   

This Challenge is like that.  It's a very straight-forward question that might not have the simplest answer.  It's up to you to figure this out! 

1.  What is the oldest city in the Americas? 

You'd think that just asking a search engine or an LLM would give you the answer and you'd be done.  Right?  

Well... if there's any deep lesson from SearchResearch, it's that things are never as simple as you'd expect... there's always something deeper and more interesting behind the question.  

Every question, even something as straight-forward as this, needs a bit of definition help.  The answer--no surprise--is going to depend on how you define "city" and how you define "oldest."  

First things first: How do we define a city?  Is it just population or "level of sophistication" or some combination?  

By the dictionary definition, a city is just "a large number of people who live fairly close together."  True, that, but not particularly precise.  What's "large" and "close together"?  

Remember that in the year 0, Rome was around 1 million people in size, while London was only around 1.4 sq km (0.5 sq mi) and home to less than 5,000 people.  Of course, by the year 537 AD, Rome's population had fallen to around 30,000 souls, while London had risen to around the same number.  

Populations come and go--cities are built, grow, prosper, decline, and sometimes lose everyone becoming less than a hamlet.  

So we have a couple of definitional questions to answer before we get to the key Challenge. 

a. how many people make up a city? 

b. how large an area does a city have to be?  (Or does population density make a city?) 

c. does the length of time a city is occupied make a difference in our question?  

I mention all of these variables because in order to answer the question, we need to pick some values.  (In some sense, it doesn't really matter which values you pick, as long as most people will agree that "this is a city at this time.")  When Rome fell to 30,000 people, was it still a city?  I'd say so, partly because of history, but also because they were fairly densely packed together.  

So, for our purposes here, a city is an assembly of more than 2000 people living in a small area that supports commercial activity, with some kind of government or ceremonial / religious functions.  (We'll ignore continuity for the moment.  If the city lasted for more than 5 years, it is--or was--a city for our discussion.)  

Once you get beyond definitions, you might think you could just ask all of the ChatBot LLMs and Search Engines this question, "What is the oldest city in the Americas?"  

When you do that, this is what you get:  

  

The answers vary based on differing assumptions that each system makes.  

Bing, for example, only shows St. Augustine, FL... but the first organic result points to the Wikipedia article on "List of cities in the Americas by year of foundation" (we'll look at that in a minute).  

Some of the systems expose their assumptions.  Gemini's reply includes the supposition for each: 

"If you consider the oldest continuously inhabited city founded by Europeans, it's Santo Domingo in the Dominican Republic, established in 1496.    If you're looking for the oldest continuously inhabited city in North America founded by Europeans, that would be St. Augustine, Florida, founded in 1565. However, if you're talking about the oldest city in the Americas overall, the answer is Caral, Peru. It's an archaeological site dating back to around 3500 BCE, making it one of the oldest cities in the world."

That's a good response, but it does NOT expose any of the other cities that might qualify.  (And is pretty North American biased as well since it lists Euro-towns before the older places in Peru, but I digress.)  

If you just look at the cities listed here and collect their founding dates (as given by the search/AI systems), you'll have this:

THIS is why doing a comparison table is a great idea--you can see the different options and the different assumptions that were made.  With this table we can look at each of these claims one at a time.  Let's do a little digging for each of these claims.  

Tlapacoya is claimed by Perplexity to date to 7500 BCE.  That's quite a claim.  By doing a bit of Google searching, it's clearly a city by 1500 BCE, but there are some artifacts going waaay back, including some rather controversial ones dated to 25,000 BCE.  (They're so controversial that we're going to ignore them here.) But where did the 7500 BCE claim come from? 

When I pushed Perplexity on this [why did you say that Tlapacoya dates to 7500 BCE] it rapidly backpedaled and claimed--falsely--that "I did not mention that date."  Harrumph.  Yes you did.  I have the screencapture to prove it.  Sigh. So this seems bogus... The actual founding date of Tlapacoya seems to be 1500 BCE.  

Footnote:  I figured out where the claim of 7500 BCE for the start of Tlapacoya comes from... it was scraped from the Wikipedia article, List of Cities in the Americas without careful verification.  Oops!  There is an error on the internet... Perplexity just forgot what it was trained on.  

Aspero was pretty clearly a city (with major buildings, large temples, and agricultural fields) by 3000 BCE.  It was part of the Caral-Supe civilization which goes back even farther. (The Caral-Supe culture seems to date to 5000 BCE, but cities started later and can be reliably dated to ca. 3700 BCE.)  
Huaricanga was also connected with the Caral-Supe culture and dates to 3500 BCE.  There are more major buildings and temples and possibly a connection to Aspero.  

Caral seems to have had several thousand inhabitants starting around 2600 BCE, centrally located to all of the Carl-Supe sites.

HOWEVER... while reading about Caral, I stumbled across a mention of site that was possibly older--a place called Bandurria.  Curious about this place (which wasn't mentioned by any search engine or LLM), I did a bit of searching and found dates for Bandurria that are around 3000 BCE--older than Caral, but newer than Huaricanga. (See Paleodiet in Late Preceramic Peru: Preliminary Isotopic Data From Bandurria)

Odd, isn't it?  A major city that is contender for oldest city in the Americas, and it doesn't show up in any of the search/LLMs.  

There are a couple other sites that are quite old e.g., Puerto Hormiga in Columbia, or Celilo Falls (aka Wyam) in Washington state--but both of these seem to be ephemeral villages or trading locations--they have long histories as temporary settlements, but never quite made it to city status.  

Bottom line:  The "oldest city in the Americas" tag has to go to Aspero (3710 BCE), with Huaricanga (3500 BCE) and Bandurria (3000 BCE) close behind. All of these cities had more than 2,000 inhabitants, lasted for many years, and were centers of commerce and religion.  

And our new table has moved Tlapacoya to the fifth position, and added Badurria into position three.

SearchResearch Lessons

1. Compare and contrast different sources.  You know, we've talked about "second sourcing" your results. In this case, I compared eight different systems (search engines + LLM chatbots).  As you can see in the table above, the answers are VERY different from each other.  In some cases, the results are just plain wrong.  (Interestingly, not because they're hallucinating, but because they trained on data that was incorrect, which then surfaced in their outputs.)  

2. Building a comparison table is handy. Not just because you can then use the table to work through the different results, but also so you can see the huge variety of results.  When the "answers" are this different from each other, you have to be fairly skeptical... which we found was the right thing to be.  

3. Remember that search results might be incomplete!  I found Bandurria because I noticed the unusual name when scanning the results.  Checking into it, I found the 3rd oldest city in the Americas... and a result that NONE of the systems surfaced!  

4. When doing search comparisons like this, make your definitions clear so people will know what you're comparing. 

Keep searching!