When I watched this week's inauguration, I noted that there were five flags hanging from the US Capitol, but that only one was the current 50-star version. I wondered why, and was intrigued by the explanation I found at https://en.wikipedia.org/wiki/Betsy_Ross_flag. Apparently, every presidential inauguration displays Betsy Ross' 13-star flag, with its stars arranged in a circle, and there were two of these. There were also two copies of another 13-star flag, though. What were those about? It seems that each inauguration gets a flag of the version that was current when the incoming president's home state joined the union, and Delaware was one of the original 13 colonies. Barack Obama's inauguration, in contrast, featured a 21-star flag reflecting Illinois' later admission. I had not known that.
