Most Americans here are probably familiar with the idea of city mottos: "Welcome to Xville, the capital of Y!" Of course there are many variants, from the brilliant to, well, Albuquerque's ("It's a Trip"). I know other cities across the world have nicknames (The City of Lights, etc.), but does the idea of an official town slogan originate in America?
The city I was born in is mentioned in De Bello Gallico, and its motto is Utinam ("God be pleased"). Can't find a source right now, but I believe that the motto originates with Charles V, Holy Roman Emperor. So you've got at least one town motto that goes back to the 16^th century.
Similarly, Paris's motto (Fluctuat Nec Mergitur, I float but do not sink) is found on counters from the late 16^th century and was officially adopted by a 1853 law.
So, while I'm not sure where the practice originates, it seems to be a common thing in Renaissance European cities.