Martinsburg, WV has a population of 17,613 and is the 2,456th largest city in the United States. The population density is 2,656 per sq mi which is 3369% higher than the West Virginia average and 2832% higher than the national average. The median age in Martinsburg is 34 which is approximately 18% lower than the West Virginia average of 42. In Martinsburg, 43% of the population over 15 years of age are married, 91% speak English and 5% speak Spanish. 42% of Martinsburg residents were born in West Virginia, 51% were born out of state, 1% were born outside of the United States and 5% were foreign born.