“Boys in blue” is a blanket term that includes all genders. It’s kind of like saying “hey guys!” when addressing a room of men and women.
“They caught the shoplifter on camera. They’re just waiting for the boys in blue to show up and arrest them. ” “Are the boys in blue on their way?” “Did you see the boys in blue riding their horses over on Main Street?”
In many countries, police forces wear white, gray, or neon vests. As such, if you say “boys in blue” outside of the US or UK, people may not know what you’re talking about.
Someone might say, “I love that boy in blue,” or, “What a dashing boy in blue! That outfit is so on point. ” This is not a particularly common usage, but you may see lovers of fine art or folks in the LGBTQ+ community using it.
If you watch the Toronto Blue Jays or Chicago Bears play, an announcer might say, “Here come the boys in blue!” as they enter the stadium.
It’s rare these days that someone would use “boys in blue” to refer to the Union Army in everyday conversation, but you might hear a history teacher or museum curator use it this way.
