As opposed to the many "photo contests" out there that are little more than schemes to make money, gain publicity, and steal the rights to your photos, this one is legitimate and worthy of your consideration: https://photocontest.smithsonianmag.com/photocontest/rules/
Deadline is November 30, and there are no entry fees.
Gerry
I've re-read the "fine print" for this contest and found that the Smithsonian DOES acquire the unlimited and perpetual use of any photos entered. (See their rules for details.) Therefore, I will not be entering this competition after all.