Smithfield, NC has a population of 11,746 and is the 3,472nd largest city in the United States. The population density is 968 per sq mi which is 435% higher than the North Carolina average and 969% higher than the national average. The median age in Smithfield is 45 which is approximately 17% higher than the North Carolina average of 38. In Smithfield, 55% of the population over 15 years of age are married, 83% speak English and 15% speak Spanish. 61% of Smithfield residents were born in North Carolina, 26% were born out of state, 1% were born outside of the United States and 13% were foreign born.