You cannot go wrong if you dress in red/white/blue for July 4th in America. Likewise, you dress in red/green and you are fine for Christmas party. Knowing specific colors for a holiday makes it easier to choose party clothes.
Personally, "wearing flag" is overdoing it (or possibly illegal). But using the color scheme should be fine.
Then, here it is. Juneteenth 6/19, the new American holiday, cerebrating freeing of slaves. On the day 6/19 of 1865, enslaved black people in Galveston, TX, became Americans under the law.
I checked out the colors for the Juneteenth.
They say it would be "blue/red/white" (as American holiday. The Juneteenth flag uses the color scheme) and "Red/green/black" (colors of pan-African flag adopted by black communities).
Apparently I can use my July 4th ties and shirts just fine for Juneteenth in coming years. Lucky enough.
The new holiday could be a triumph of civil rights movement, or could be a political bargaining piece that Republicans thought can be used in another deal making or publicity spin. Well, I have no need to be political or sarcastic here, and can just cerebrate. Either way, the holiday is now implemented.
Our institute will observe the holiday on 6/21 Monday (tomorrow). We are told that "non essential employees will receive holiday pay and are not expected to work". I'd be working to take care of something that were already planned, though (may show up later than usual).