Don't know which shirt you should wear when marching on April 22? Here is a choice for you: a March for Science shirt from Dr Seurss - the Lorax quote.
The Lorax: Unless - March for Science shirt
We should get t-shirts for the march!!
You can get this Unless shirt at iFrogtees $21.99 (t-shirt, hoodie, tank). Mug, Hat are also available
Another suggest for Earth Day March shirt: I'm With Her shirt or Bill Nye Science shirt.
Science is Real! More choice for you here: March for Science shirts