I think it’s important to remember that Tolkien’s world is definitely not just a physical place but a spiritual and magical place, so the effects of the dark and evil things on the world have more of a hold on the land. The Dead Marshes, after all, are a physical embodiment of a massive war, and the souls of the dead still influence the land thousands of years later. It’s entirely possible that the Witch-King’s presence for so long in Angmar and Fornost is still affecting the land, like a spiritual taint that keeps people from resettling the once-prosperous territory. It might even be why Gandalf takes such an interest in Hobbiton, because it is almost a miraculous safe haven in the midst of dangerous and scarred lands. Just leaving the safety of the shire almost kills the hobbits, from evil trees to black riders to collaborators in Bree. The land is blighted.

Remember Tom, Bert and Bill? The three ate at least "a village and a half", before Gandalf and co. stopped them.
No wonder population growth had been nothing like in our age.

This is just pure speculation, but it's possible that after the Fall of Arnor the land was under some kind of curse that made it more dangerous and that curse was broken when Aragorn became King.

As a teacher, i really appreciate the "several million bananas" metric.
The dry wit with a joke given no explanation, continuing without missing a beat as if nothing happened, really rewards paying attention.
Nice.

In a lot of the myths that inspire Tolkein, the strength or weakness of a land is a reflection of the king. When the king is vigorous the land prospers, when he is ill, the land suffers too. Eriador has no king at all and thus perhaps this is why conceptually, it is a dying land.

As an Ecologist, my personal biggest gripe about Eriador's lack of change since the fall of Arnor is that a lot of the flora and fauna seem to also be stagnant. Elrond, Treebeard, and many others lament the deforestation of the region, but you'd think a thousand years or more of minimal land use would allow for a whole new forest to blanket the region? As far as I know, outside the Old Forest and the Chetwood we only hear about thickets and small groves across most of the area. Most of it seems to be portrayed as heathland, marshes, and degraded landscapes when it should have returned to a climax forest community with a ton of wildlife

The land stayed empty for a thousand years for the same reasons the lands in and around Mordor stayed empty for much longer after Sauron lost the ring and “died”.

Wasnt the argument always that Tolkien only included towns and settlements pertinent to the story and that those that didn't impact on the tale were just ignored?

We are reading of course from a Hobbits perspective

The idea that Eriador could be resettled while Sauron lived is not realistic.

Eriador is the middle earth equivalent to Tschernobyl

I think there were still things like barrow wights, wargs, trolls, and occasional orc bands that kept people from leaving their homes. Maybe that’s why it didn’t bounce back

I think Tolkien's propensity to leave vast areas of former conflict destroyed or abandoned comes from his experience at the Somme. There are World War 1 battlefields that are still unfit for human existence. In some respects you could imagine that the great evil that flourished in those areas had a major effect on lesser established places in the region. The plague itself was a potential caused by such evil.  The old forest has Tom Bombadil and the Shire is just far enough that the worst suffering didn't quite reach there, which would explain why Bree is quite close to the Shire.

I do like the LoTR online map of the area though. It does make some decent sense that after thousands of years some of the region has recovered into loose cities and settlements.

As a boy captivated by Tolkien's world, I used to pore over his maps of Middle Earth and I would often wonder what it'd be like to visit the unpopulated regions of Eriador.  Minhiriath seemed a cool place to set up a cabin and camp out.

About the population of Eriador, don't forget that the fellowship chose the course west of the mountain, because it was
> "much rougher and more barren than in the green vale of the Great River in Wilderland on the other side of the range, and their going would be slow; but they hoped in this way to escape the notice of unfriendly eyes".

Something else to add: Eriador in the Second Age was full of trees. Good for lots of races to live, especially men and elves. The Numenoreans slowly deforested it over the course of the Age to maintain their immense navy, such that by the Third Age the forests were all gone, except for a few woods here and there. The vast expanse of rolling grassland was not an inviting place for resettlement, to say nothing of the constant wars during the period. So it mostly remained empty.

I'm sure I don't just speak for myself, the bananas clarification really made sense of the distance for me.

if considering The Hobbit and the description of the troll cave it would seem that there are more to the lands in terms of population, because they have preyed uppon the local humans for a while. Maybe Isolated farmsteads was the norm outside the Shire and Bri in many areas except places like barrow down, weathertop and the old forrest, orcs and wolves also could periodically torment the lands.
The Dunedain while protecting some areas comes across as fully nomadic covering large distances, so they likely did not stop all raiding, and we even have an accord of wolves invading the shire on one occasion.
Climate and famine also means there is a limmit to how big the population can grow, Bilbo himself experienced one such famine and he was by all accounts well off by hobbit standards, less well of hobbits might have died in famines.

Gondorian resettlement of just 10.000 people would do wonders in accelerating Arnor growth.

Aragorn mentions that the Bree-folk live ‘within a day’s ride’ of mortal peril—I think it quite likely that Eriador in the Third Age was quite heavily populated with Orcs and other malicious creatures, even since the fall of Angmar. This would mean that the limited number of folk actually living there are all the Rangers could afford to protect, and that no kingdom of men could make the place safe short of a long military campaign that was too costly at the time.

I think that it is likely that Sauron had long term plans that hinged on Eriadors depopulation.  If you look at the timeline of Gondor’s history you can detect a long term plan to erode Gondor’s strength.  I always imagined that the same was happening to any kingdom that tried to get started in Eriador