Holly, CO has a population of 932 and is the 15,580th largest city in the United States. The population density is 1,285 per sq mi which is 2481% higher than the Colorado average and 1318% higher than the national average. The median age in Holly is 32 which is approximately 12% lower than the Colorado average of 36. In Holly, 72% of the population over 15 years of age are married, 58% speak English and 41% speak Spanish. 43% of Holly residents were born in Colorado, 38% were born out of state, 0% were born outside of the United States and 19% were foreign born.