I certainly have. WUWM has the answer, courtesy of local historians.
Thinnes says it was that combination of independent spirit and manufacturing might led South Milwaukee to establish, early on, its own infrastructure including a water filtration system, sewer system and its own street and address scheme.
“South Milwaukee, they didn’t really feel they were a continuation of the City of Milwaukee, so they tried to keep their own identity. And when this whole process started, they decided, no, they were not going to do it; they were going to keep their street numbering system and keep their street names,” according to Milwaukee address history buff Carl Baehr.