The Triangle region of North Carolina includes the counties: Chatham, Durham, Franklin, Granville, Johnston, Orange, Wake; and sometimes Harnett, Lee, Nash, Person, Vance and Warren, as indicated by the red and orange colors on this map from a Wikipedia article on The Triangle.


Primary cities
Raleigh 374,320
Durham 208,816
Cary 125,460
Chapel Hill 51,519

Suburbs with more than 10,000 inhabitants
Apex 31,000+
Carrboro16,500+
Clayton 16,000+
Garner 24,500+
Morrisville 14,000+
Sanford 23,000+
Smithfield 11,500+
Wake Forest 20,000+
Holly Springs 15,000+
Fuquay-Varina 12,000+

Suburbs with fewer than 10,000 inhabitants
Angier
Bahama
Bear Creek
Bennett
Benson
Bonlee
Bonsal
Broadway
Buies Creek
Bunn
Bynum
Carbonton
Centerville
Cleveland
Coats
Corinth
Creedmoor
Dunn
Efland
Erwin
Fearrington
Feltonville
Four Oaks
Franklinton
Friendship
Goldston
Gorman
Green Level
Gulf
Haywood
Hillsborough
Kenly
Knightdale
Lillington
Lizard Lick
Louisburg
Mebane
Micro
Middlesex
Moncure
New Hill
Oxford
Pine Level
Pittsboro
Princeton
Rolesville
Rougemont
Roxboro
Saxapahaw
Selma
Siler City
Silk Hope
Wendell
West Smithfield
Willow Springs
Wilson's Mills
Youngsville
Zebulon

Lists of cities and towns and the population numbers are from a Wikipedia article on The Triangle.