Headquartered in Phoenix, AZ, CSK Auto has experienced sustained growth since its inception in 1969 through a combination of acquisitions and a well-managed program of store construction and expansion. CSK currently owns and operates more than 1,260 retail auto parts stores in 22 states under the brand names Checker Auto Parts, Schucks Auto Supply, Kragen Auto Parts, and Murrays Discount Auto Stores, generating a combined annual revenue in excess of $1.9B. CSK has the number one market position in 22 of the 32 geographic markets in which it operates, based on store count. In July 2008, O'Reilly Auto, Inc., another giant in the automotive parts retail industry, completed an acquisition of all outstanding shares of CSK stock. O'Reilly intends to continue operating CSK as a wholly owned subsidiary.

Long a hotbed of manufacturing might, the Greater Milwaukee region has, in recent years, seen a growth in its educational, health, and social services sectors, which now accounts for 22.4 percent of all employment in the region.