As we discussed on our first quarter conference call, the beginning of the second quarter got off to a slow start as we suspect a good amount of the spring cleanup business was pulled forward from April into the first quarter, as a result of the earlier-than-normal mild temperatures. We expected May sales to return to a more normal seasonal pattern, and they did. Through May, our comparable store sales results were within our expectations. However, business was significantly softer than we expected in the first 3 weeks of June. This slowdown was chain wide, and we cannot point to any specific cause other than to cite that most of retail seem to have a tough June. And after a strong increase in miles driven in May of 2.3%, we suspect June's number, when reported, will be down.
The end of June finished up somewhat better, resulting in our 2.5% comparable store sales increase, coming in at the top end of our revised guidance. From the first quarter to the second quarter, we saw the biggest deceleration in comparable store sales in cold-weather markets, where the early spring weather shifted more business into the first quarter. Since the core stores have a significantly higher percentage of cold-weather market stores, we saw the biggest sequential impact in the core stores. Although these stores did generate positive comparable store sales for the second quarter, the acquired markets continue to generate strong comparable store results with our buildout of the Professional business.