Editor's note: The following is part of a series of stories that take a deep dive into the demographics and firmographics of small and midsize businesses in the United States. The findings are derived from surveys distributed from November 2010 to January 2011 to 2,223 owners of businesses with less than 500 employees.

Climate, cuisine, style, dialect—they all vary from region to region throughout the country. And the same same holds true for the small businesses that form the backbone of the U.S. economy.

Using surveys from more than 2,200 people who own business with less than 500 employees, along with data from the U.S. Census Bureau, American City Business Journals (the parent company of Portfolio.com) put together a profile of how these companies differ from region to region. Godfrey Phillips, ACBJ's vice president for research, who reviewed the surveys along with analyst Jessie Shaw, sought to determine where businesses are struggling under the weight of the turbulent economy and, conversely, where entrepreneurs have weathered the storm.

Click through the following pages to see how the nation's four primary regions compare in terms of small-business vitality, which ones are experiencing the most growth, which are seeing the best sales gains, and which are doing the most business overseas.