Because Wyoming is one of those territories with a smaller population than Washington, DC.
As of 2019, Wyoming’s population was 578,759; DC’s was 705,749.
Yet Wyoming has two senators (John Barrasso and Mike Enzi) and one Congressperson (Liz Cheney), all three of whom have full voting powers. D.C. has the estimable Eleanor Holmes Norton as their non-voting representative and…no senators.
I’m feeling strongly this will change after 2021 but until Washington has full representation in our Congress, I’ll continue not to remember Wyoming on a U.S. map.