Why do I see USA spray painted on the street in many different towns?

I've noticed this all over California.Why do I see USA spray painted on the street in many different towns?
In response to all the ';Viva Mexico'; paint that you probably also see.Why do I see USA spray painted on the street in many different towns?
my best guess is that it is in response by americans to the influx of illegal hispanics who, as insinuated by the media, are trying to claim USA for their own, imposing their mores and desires upon legal citizens while demanding rights and government services...