The thing is, almost all the advances during Reconstruction were undone by Jim Crow era laws. It wasn't until the Civil Rights movement that the promise was actualized. You could in some way consider the civil rights sites to be part of the same thing as reconstruction sites.

US will leave UNESCO again. Which means we'll likely see no new nominations until He Who Must Not Be Named leaves office.

http://foreignpolicy.com/2017/10/11/u-s-to-pull-out-of-unesco-again/

Disappointing but seemingly in line with the rhetoric on the issue

And coming hot on the heels of the USA gallantly "boycotting" the 2018 World Cup as well perhaps isolationism is the best way to Make America Great Again?

Does anybody understand the consequences of this?
Will it mean that all American sites (plus maybe Puerto-Rico) will be DELISTED?

No, that already happenned (in 2011) and no site has been delisted. It concerns "only" their financing contribution, which is a big part of the finances of Unesco. It looks like a tantrum due to the inscription of a palestinian site (symbolic) this year.

and US stays as observer state.

Strange. Israel itself is still in the game. (althought they cut funding too)

Is this just a pretext to do something they (Trump) had already been planning to do?

A sad day. All those great maritime and iconic NYC/Chicago and other interesting sites that the NPS, (also de-funded by our Great Leader) and basically run by volunteers at this point), will sit there collecting dust until hopefully the next President. This is really just to make Trump and Tilllerson PR for being "strong allies of Israel." Meanwhile, Tillerson calls him a "f*cking moron." It's a disgrace and I went to bed and woke up heartbroken.

Sad day for the United States, all US sites should remain, we were out of UNESCO from 1984-2003 and even added new sites during that time period.

Official press release. US withdrawal will not come into effect until December 31st, 2018.

https://www.state.gov/r/pa/prs/ps/2017/10/274748.htm

Israel is out too.

"Israeli Prime Minister Benjamin Netanyahu said Israel plans to follow suit."

yes Israel too.
This morning, Irina Bokova was invited by France Info (french radio). She obviously regrets this decision and insisted on the universality of Unesco, that means Unesco is impartial and not anti-Semitic. The US and israelian positions are quiet worrying and dubious.

EDIT: they also underlined that this decision intervenes during a specific moment, that is the election (today). Atlantico website (more or less extremist) says it is due to the qatari representative who is a terrorist. Their opinion, because i am not sure it's true.

Ah the Gulf states geo-politics has made it to UNESCO as well.

Qatar is being painted as the funder of all evil by its neighbours at the moment, so not a surprise UNESCO is being pulled into it too. There is plenty out there about the breakdown in relations in the Gulf but this podcast episode from Planet Money gives a good run-down on it.

I'm not suggesting that Qatar is innocent of what it is charged with, however it is worth bearing in mind this geo-poltical game being played if you see anything negative about Qatar (or their hosting of the 2022 World Cup/ dealings with Paris Saint-Germain football club etc) in the next few months.

It's anyway a pretext, because it was not the case in 2011. Israel and US are not pure as the driven snow, it's easy to say Unesco is anti semitic :)

Strange thing to say UNESCO is anti-semitic. The new General Director elected today being jewish.