My question involves civil rights in the State of: delaware

I have never put my house number outside my house because I don't want to advertise my address. The mailman knows my address and the ambulance has gps. But my reasons are beside the point.

I received a letter from the town that states if I don't attach a reflective address number outside my house there will be a $50 fine. Other residents are upset too. Seems like it's and invasion of privacy. Is this a violation of my rights?