Les Aspin held that district with Janesville, Kenosha, Racine, and some Milwaukee burbs for 20 years. It's not Janesville that helps Paul Ryan. He just lives there. It's parts of Waukesha County which is one of the biggest Republican strongholds in the nation.
Actually, Janesville is the county seat of Rock County, which voted Dem in the election. It’s south of Milwaukee. Waukesha is the western Milwaukee suburban area.