Now that I’ve gone over some of the factors that cause a nation
to age [x], I think it would be useful to go through each one separately. This
post will focus on how political autonomy and independence allows a nation to
reach adulthood.

Not only that, but what you’ll also see is that they go
through growth spurts right before gaining independence; their status as an
adult is solidified once this independence is gained. In other words, it’s the resistance that first sparks the aging.

It’s also important to mention that
chronologically-speaking, nations will still consider themselves to be older
than others, regardless if one of them became an adult first. There are late bloomers
like the Italy brothers and quick bloomers like America. The best comparison I
can think of is that anything to do with gaining independence is akin to the pubescent
period for a personification.

That said, let’s go through some examples.

America: 

In the following three panels, we see America go through three
developmental changes. In the first stage, he holds a more compliant attitude
towards England and helps him in the French-Indian War. Notice the tag of “Young
America” attached to him.

This compliance begins to wane as America was heavily taxed and financially drained by England following his involvement in the war. Notice how he’s a slightly
older child here.

Then, when America begins fighting for his independence, he’s clearly gone through another growth spurt. 

We also see in the years leading up to his independence – as he becomes even more economically and politically sufficient – that he grows pre-emptively.

Lastly, there’s the imagery that Kumajiro uses with dolls to
represent England’s relationship with America and Canada. America is the rowdy
Baby Bear; put another way, it’s like a teenager fighting for freedom from
their parent. Once that freedom is gained, only then will they become an adult.

Canada: 

Canada’s growth occurred at a much slower rate than America. He wasn’t an economic powerhouse like the latter.
While he remained as a young child, America appears to be in his pre-teen
phase.

In the years following America’s independence, Canada ages,
but he still has the lanky and awkward appearance of a teenager. He hadn’t yet
gained his autonomy yet, the missing factor to the age equation.

Here’s Canada after the Battle of Waterloo. 

Pay attention to the roundness of his face.

And here’s him during the war of 1812 [right], vs how he
looks in present strips [left]. There’s a notable difference in age. 

Likewise, we also know that when Canada upgrades to the semi-dependent
status of a Dominion, the autonomy is enough to allow him to reach adulthood.

Italy: 

We know that Italy is around the age of a pre-teen during the
Austrian War of Succession. He’s not quite a teenager, or at least not an older
one given how short he is in comparison to Austria.

During the Battle of Custoza [whilst raging his third war of
independence], there’s a considerable increase in age. Once again, we see an
example of a nation pre-emptively growing right before they attain independence.

Once Italian Unification is complete, there’s no doubt that
Italy has become an adult.

Romano:

Romano’s path to adulthood occurred in the exact same manner
and timespan as Veneziano’s did.

He’s around the same age as Veneziano during the Austrian
War of Succession.

He’s noted to have stereotypical teenager behaviour in the
years leading up to his independence from Spain.

Before independence, he appears to be in his late teen
years.

Once unification occurs in the panel I provided above, he’s also clearly an adult.

With all that in mind, it’s important to mention that chronological age is how the nations organize themselves
in terms of perceiving their elders. I know this may come across as obvious,
but it still needs to be said.

Despite becoming an adult later than America did, Romano
still sees himself as older than America and even takes it upon himself to give
him political advice.