The Civil war... I'm wondering, what can you still notice from that to date, if anything?
It was quite the thing, a major rift in the country, very intense feelings, heavy losses on both sides, etc. Such deep-seated events take time to dissipate and often pain, grief, hatred, and so on are passed on from generation to generation on either a conscious or subconscious level.
Since only some 4 generation are in between then and now, that's not much at all.

So does it have long-term effects on people, society etc? Is there really a general sense of union among the south & north? Or is this only skin-deep and if something triggers it, it surfaces strongly again?

I could probably Google, but what better way to learn about this than from Americans themselves that likely have civil war stories & history in their family line.

I live in what is considered the 'Deep South'.
While the essence of the Civil War is no longer publicly displayed it exists in the people and thus exists in the expressionism of the people.
Plus, around the country there are memorials, landmarks and communities have festivals and parades.

While the Confederate flag is a no-no publicly, it is still pretty easy to find personally.
Many catch phrases are still common too.

The U.S. civil war was the result of a few conditions;

Economics, with the mostly agrarian south wanting to sell it's products to markets in Europe at a higher price than the rapidly industrializing north wanted to pay. And wanting to buy manufactured goods from Europe at lower prices than the north was offering.

State rights versus federal authority. This continues today with arguments over abortion, taxes, schools, racial discrimination, and even hy-way speed limits.

And of course slavery.

My folks came here long after the war was over but;

Most of these things are still argued over today. And sometimes quite heatedly. But instead of north vs south, they've become more of rich vs poor, left vs right, religious vs non-religious. And of course the race issue is still very prevalent.

Oh............the war of Northern Aggression!
These guys above have given some very brief (but good) responses, it's not a topic that can begin to even be touched on in this forum but I'd like to say if you really want to get a good understanding, study.
I can tell you this; many northern families were somewhat effected by this war but EVERYONE in the south was effected very deeply!

Keep in mind the quote "history is written by the victors".

One book I'd highly recommend is titled "THE SOUTH WAS RIGHT".

Yes, just like in 1918, 1945, and every other war, the winners write history and the losers live it. The south should have never started the war. They didn't have the resources to win it. And the area has paid for it ever since. Whether their motivations were right or wrong is a debate that still continues today.

Thank you, guys, very interesting to read!

@TOM, you mention catch phrases. Could you give an example?
I know what a catch phrase is but not entirely sure what to think of in concerning this.

"He's a Rebel" = Juvenile delinquency
"I feel like a slave" = demanding job
"Slave Town" = low income housing blocks.
"Harsh Taskmasters" = demanding/difficult boss
"Underground Railroad" = hidden path/sequence

Just a few...
Many references are so common ya don't even realize they are connected to the Civil War or the emancipation of slaves. Plus, as time progresses the more obvious ones slowly fade away.

When I was growing up "Back of the bus gang" referred to a group of people who were shunned by society.
Nearly all references are derogatory in some way towards someone.
The worst ones (which I will not include out of respect) are specifically discriminatory and hurtful.

Thank you for taking the time to elaborate, Tom!

What most don't realize about the civil war,
it was, initially a war of economics.

All wars are issues of economics.