Historically Rock County has always been apart of WI-01 along with Kenosha, Racine and Walworth counties. In terms of settlement, this area saw the highest % of emigrants from New England and Upstate New York. The split only occurred for the first time in 2001 as part of an incumbency protection plan for Paul Ryan and Tammy Baldwin. Both WI-01 and WI-02 were Toss Up seats in 1990's. Dane County outside of Madison was not as extremely Democratic as it is now and the surrounding counties were pretty Republican down ballot. The idea was to give Democratic western Rock County and Beloit to shore up WI-02 and then compensate for WI-01 with blood red southern Waukesha County. Almost immediately however, Dane County swung/trended hard to the left and the neighboring counties either went along or had no ability to counter Dane County. In terms of WI-01, the deal probably saved Paul Ryan a couple times (2006 and 2008) as he probably loses if western Rock/Beloit was in his district instead of southern Waukesha County.
Paul Ryan would absolutely have lost in 2012 if not for gerrymandering. Case is stronger in that year than it is in 2006 or 2008.
