A large factor in the advancement/financial disparity between the U.S./Canada and its neighbors to the south is the **difficulty of colonizing areas in tropical/subtropical climates vs. colonizing temperate areas**. The climates of these regions are vastly different. Very little of Earth's land lies in the temperate zone of the southern hemisphere.

(If I remember correctly this is somewhat covered in Jared Diamond's [Guns, Germs, and Steel][1], but of course anyone playing Civilization or a Paradox history game such as Europa Universalis knows you stay away from the jungle.)

(From [Reference.com][2]: "Areas with temperate climate enjoy weather conditions without large temperature extremes and with rainfall occurring throughout the year.")

Before modern medicine (and even today), **people living in warm or hot areas were more subject to disease** (such as malaria, which continues to kill hundreds of thousands of people each year in tropical climates throughout the world), with livestock and the crops that have generally sustained civilization more subject to disease as well. Additionally, **the grains and other crops such as wheat and potatoes that kept civilization going were grown in temperate climates** and were less likely to die off due to extreme variations in weather. 

For more on the crops that sustained settlers and where they were grown, see T.E.D.'s answer on another related question [here][3]. Note he refers to **indigenous peoples being removed from temperate areas for farming land** - one of the reasons you don't have large indigenous populations in temperate countries like the United States or Argentina, both of which received the largest influx of immigrants and both of which conquered and removed indigenous people. Note that Argentina has a larger GDP per capita than most Latin American countries, and has historically been somewhat more stable.

Combine this with the difficulty of taming the jungle vs. taming a temperate forest, and the ease of colonizing the United States vs. that of colonizing much of, for instance, Brazil becomes apparent.

**Please see a simple map of the areas in temperate zones vs. the areas in tropical zones below, followed by a more complex climate map.**

[![By KVDP - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=27385077][4]][4]

Below is the Koppen-Geiger map. T.E.D. posted a map similar to the one below in his answer that I linked above, stating that **areas in green and tan are** good for growing crops. In the case of this map below, which is slightly different, **dark purple isn't terrible**. Meanwhile, these areas are not as prone to disease.

[![enter image description here][5]][5]

**Compare these to pretty much any GPD per capita map**:

[![GDP per capita map][6]][6]

As Santiago wrote in a comment below, the area of Asia that lies in the temperate zone seems to be an anomaly between the first temperate/tropical zone map and the GDP map, but it is important to note that this area is sometimes called the "[third pole of the world][7]" for a reason (this is the reason I updated with the Koppen-Geiger map). While this area of Asia is in the temperate zone, the actual climate is cold and arid. Meanwhile, other anomalies between the Koppen-Geiger map and the GDP map lie in the middle east and Venezuela; oil explains the discrepancy.

First of all, note that **the colonizing nations were all located in the temperate zone of the northern hemisphere, in areas that are green in the Koppen-Geiger map.** 

Secondly, note that **many of the states in the United States with the lowest income are in the subtropical areas of the country** (only Mississippi shows this on the GDP map, but it remains true for the much of the southeast). These states still have a high GDP per capita compared to the nations below the Tropic of Cancer. I currently live in Florida, which benefits from a robust tourist industry and isn't as bad off as where I'm from in Alabama, and I can tell you that not many people lived in Florida until the invention of air conditioning and modern medicine (and without either of those I wouldn't live here). There is little local history other than small settlements dotting the state. Note that even the hottest parts of Florida are above the Tropic of Cancer. 

For another example, see that tiny part of Australia that lies in the temperate zone, and the borders closest to it? See how the green areas are all in or near this zone? Compare it with this map of population density:

[![Australia population density][8]][8]

**Most Australians live in or near the edge of the temperate zone, in the green areas of the Koppen-Geiger map**, and even those people were dragged there from England, which was exactly in the middle of the temperate zone and is as dark green as you can get. One might also compare Australia and New Zealand and their places in or near the temperate zone and their higher GPD per capita than their neighbors to the north.

Now take a look at **Uruguay, Argentina, and Chile, all of which have a relatively high GDP per capita compared to the rest of Latin America. These are the only major parts of South America in or near the temperate zone, and are the only areas that are green or tan.** They are [relatively free of malaria risk][9], and their higher GDP per capita compared to other Latin American countries likely corresponds to their climate.

On a similar note, as I mentioned in the beginning of this post, Argentina's climate caused it to [receive a vast number of immigrants in comparison with the rest of the world][10], largely displacing its indigenous peoples. 

> The strength of the immigration and its contribution to the Argentine
> ethnography is evident by observing that Argentina became the second
> country in the world that received the most immigrants, with 6.6
> millions, second only to the United States with 27 millions, and ahead
> of countries such as Canada, Brazil, Australia, etc.

As for politics: **the politics of places that have a higher GPD per capita and less strife between indigenous peoples and immigrants are generally better over the long term**. 

---EDIT---

Since another answer by Luís Henrique called my claims out specifically (all's fair, I have no issue with this), I will attempt to answer issues brought up in said answer. I hope my tone here is not seen as aggressive, though it will likely come off as argumentative to some. No offense to Luis or any others who disagree is intended.

>  1. "difficulty of colonizing areas in tropical/subtropical climates vs. colonizing temperate areas" - That this is clearly not the case
> can be easily shown by the fact that Latin America was colonised a
> century before North America.

Latin America wasn't "colonized" a century before North America, it was conquered, largely with the help of armies of thousands of native renegades (not with 500 Spanish soldiers, etc. etc.). The vast wealth from said conquering fueled a continued surge in "colonization" efforts, which consisted of controlling people who already knew how to survive in their own land. Actual self-sufficient colonies of Europeans would only gain footholds in good climates, and even then only when technology was sufficiently advanced. 

> 2. far from an inferno of tropical diseases, the whole "new world" was an epidemiological paradise. None of the main epidemic killers -
> malaria, smallpox, plague, cholera - were even known in the Americas:
> they were all brought from Europe, in which, the temperate climate of
> the area nonwhitstanding, they had been killing millions of people for
> hundreds of years.

Regardless of whether they existed BEFORE colonization, they certainly existed DURING colonization. How they came to exist in the jungle is not at issue. Meanwhile, the constant presence of malaria was not much of an issue for most of Europe; pandemics sweeping through areas that had enough food to sustain large populations but not enough technology/information to be able to combat said pandemics were the main problem, and populations recovered rapidly given the abundance of arable land in said areas. There is no argument being made that disease was not an issue for colonists in temperate climates. The argument is that disease, especially cholera and malaria, was not nearly as devastating in these areas as it was in tropical climates. Disease - especially mosquito-borne disease - is simply more prevalent in hot areas where freezes do not regularly reduce insect populations. Just ask anybody in the southeast U.S. who has had to deal with rampant mosquito populations after a mild winter.

> 3. Those diseases [...] were by the way defeated in the 19th century

Malaria remains a threat in some areas in Latin America, and it was certainly not defeated in the 19th century. Its origins were barely understood until the end of the 19th century, and the construction of the Panama Canal in the early 20th century nearly failed (due to nearly every worker coming down with malaria) before the powers attempting its construction figured out preventative measures. While quinine as a treatment for malaria was discovered prior to this, it is doubtless that the common poor had a hard time coming by it, as the trees that provided it grew solely in areas surrounding Peru and demand was worldwide.

> 4. To imagine that climate provides an effective barrier against their spread North of the Tropic of Cancer is false, and very contrary to
> historical evidence.

Climate provided an effective barrier to malaria north of subtropical climes, not north of the Tropic of Cancer. It was, in fact, the leading killer of colonial women in the southeast United States in the 19th century. As I have said earlier in this post, the southeast United States is the poorest area of the nation, and hot/humid areas such as Florida did not receive large influxes of European settlers even after Florida was won from Spain. And in spite of the existence of malaria in subtropical climates, its larger prevalence in areas that are most hospitable to mosquitos - tropical climates - is obvious on its face. 

> 5. Latitude is not the only factor in determining climate; altitude also counts and makes the climate of most of the western parts of
> Souther America, as well as Mexico, quite cool and even chilly - but
> neither Mexico nor the Andes correspond to any pockets of prosperity
> or political stability.

As I have explained (when I brought up "the third pole of the world"), high, chilly, mountainous areas do not make for large populations of wealthy individuals. There is no argument being made that mountains make for better colonization than jungle.

> 6. Far from obsting the colonisation of South America, its tropical climate made it easier, and more profitable, providing the relevant
> European powers with a foreign base to produce foreign goods, which
> could find excellent prices in Europe. It provided South and Central
> America with an economy that was complementary to Europe's.

Yes, extracting wealth from conquered colonies rich in exotic goods was profitable for the colonizing powers. Was it profitable for the average person living in the colonies? Was it profitable for the exploited natives or the slaves that had to be brought in when the natives died of disease? No, even you argue the opposite:

> 7. That immediate prosperity, unfortunately, was not a boon, but a disgrace to the regions aflicted by it, because it originated a social
> layer of large proprietors, entrenched in privilege and willing to
> subordinate their countries to foreign rule as long as that rule
> preserved their privileges.

The U.S. and Canada were run by colonists (to a large extent) for colonists, and colonies had been founded exclusively by Europeans moving to an area that had a climate just like the climate they were leaving. Argentina was founded in much the same way, as I have argued. These countries drove out native peoples to found their self-sufficient colonies.

The neighbors to the south were run like companies, their sole purpose to extract value. The people were not driven out; they were the exploited workers. The peoples could not be powerful and self-sufficient given the technology and crop packages of the settlers there. This accounts for much of the disparity between the U.S. and Canada and their neighbors to the south, and is a direct result of the different climates and how the land could be used.
 
> 8. Conversely, where the temperate climate matched with a metropolis that could or needed get rid of significant numbers of population,
> colonies with a more democratic structure and more loose ties to the
> metropolitan centre developed. Where temperate climate didn't match
> this, as in Uruguay, Chile and Argentina, the local structures were
> similar to those in the tropical area, though much more sparsely
> populated (Uruguay is about the same size of the the Brazilian
> southernmost state of Rio Grande do Sul, and albeit an intensive drive
> on immigration to increase its population in the late 19th century, it
> still has a population corresponding to a third of that of Rio Grande
> do Sul).

It’s hard to tell what is being said here, but these areas extended from subtropical to temperate, were better off, and as I said before Argentina received the 2nd most amount of immigrants of all European colonies. The part of Brazil in this area, Rio Grande do Sul, is 1.6 times the size of Uruguay, its larger population is centered around Porto Alegre, a port where five rivers converge and the [chief industrial and commercial center of Brazil][11], and Uruguay’s GDP per capita and its GDP per capita are equitable.

> 9. The apparent prosperity of Uruguay and Argentina in the early 19th
> century was correspondingly delusional, resting, as the economy of all
> of South America, on the export of primary products - in their case,
> meat.

So they could grow enough food to feed themselves, then enough grain or arable grassland to feed enough cattle that they could get rich off of exporting meat, and this is "delusional" prosperity? It sounds like regular prosperity to me, the type of prosperity that could only come from a place with regular rainfall and a climate hospitable to the European crop/livestock package. This is, in fact, the same kind of cattle-focused prosperity that led to the expansion of the U.S. into the western states. Meanwhile, once again, the GDP per capita in these places is still much higher to this day. That is not delusion.

> 10. In contrast, where the tropical climate, exceptionally, wasn't coupled with the rise of a colonial compradora elite, as in the case
> of Costa Rica, a less inequal and more stable society arised, and
> probably was unsuccesful at the development of a local independent
> capitalism due to its small size, rather than by climate or the other
> problems that plague Latin America.

Tropical climes were coupled with the rise of colonial elites precisely because they were tropical climes in which value was extracted but in which immigrants from Europe did not want to live. Meanwhile, one might argue that Costa Rica's main problem developing local independent capitalism was that it was covered in jungle.


  [1]: https://books.google.com/books/about/Guns_Germs_and_Steel_The_Fates_of_Human.html?id=PWnWRFEGoeUC&source=kp_cover&hl=en
  [2]: https://www.reference.com/science/temperate-climate-390b94c325f6d5bb
  [3]: http://history.stackexchange.com/a/21079/24322
  [4]: https://i.sstatic.net/wn8Zr.png
  [5]: https://i.sstatic.net/5dOeo.png
  [6]: https://i.sstatic.net/OD2u9.jpg
  [7]: http://www.eos.unh.edu/Spheres_1110/wsc.shtml
  [8]: https://i.sstatic.net/5qUGu.jpg
  [9]: http://www.netdoctor.co.uk/medicines/a5931/guidelines-for-malaria-prevention-in-central-and-south-america-and-the-caribbean/
  [10]: https://en.wikipedia.org/wiki/Indigenous_peoples_in_Argentina
  [11]: https://en.wikipedia.org/wiki/Porto_Alegre