Speciosa the tropical one- is controversial because it needs whacked down in the fall, or it can give the monarchs a disease. It regrows and is fine then. Syriaca isn't local either, but naturalized.
Monarchs and other butterflies tend to return to where they were raised, so some areas see fewer than others.
PS- meant to add. State property such as roadsides belong to the gov't. They call it poaching. Their property lines and easements are filed in property tax offices and public domain viewing. Same as your property boundary lines
