the Durham-Chapel Hill, NC MSA.   The Research Triangle region encompasses the U.S. Census Bureau's Combined Statistical Area (CSA) of Raleigh-Durham- Cary in the central Piedmont region of North Carolina. As of Census 2010 the population of the Raleigh-Durham-Cary CSA was 1,749,525. The Raleigh-Cary Metropolitan Statistical Area (MSA) as of Census